Musa is the class teacher of a class of 45 students. He wants to split them into three groups by age. If a third of the class is under 11 years, and two-fifths are above 11 but under 13, how many students will be in the third group (13 years and above)?
The first group is a third of the class which is (1/3)*45 = <<1/3*45=15>>15 students
There are 15 students in the first group, so there are 45-15 = <<45-15=30>>30 students
The second group is two-fifths of the class which is (2/5)*45 = <<2/5*45=18>>18 students
There are 18 in the second group so there are 30-18 = <<30-18=12>>12 students left in the third group
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Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
You are solving math problems. Here are some examples of how to solve the task:

A fifth-grade class went on a field trip to the zoo, and their class of 10 students merged with another class with the same amount of students. 5 parents offered to be a chaperone, and 2 of the teachers from both classes will be there too. When the school day was over, the students could choose to go home and 10 of them left. Two of the chaperones were parents in that group, so they left as well. How many individuals were left at the zoo?A total of 10*2=<<10*2=20>>20 students went on the field trip.
Some chaperones showed up, letting the group grow to 20+5=<<20+5=25>>25 individuals.
The teachers had to come as well, making the group as big as 25+2=<<25+2=27>>27 individuals.
When the school day ended, 27-10=<<27-10=17>>17 individuals were left.
A couple of chaperones followed suit, leaving 17-2=<<17-2=15>>15 people at the zoo.
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Karen's students are about to take a standardized test. Karen gets a $500 bonus if their average score is above 75, plus an extra $10 bonus for every additional point the average score increases above 75. So far, Karen has graded 8 tests, and the average is 70. Given that each student can have a maximum score of 150, what combined score do the last two tests need to have for Karen to earn a $600 bonus?First subtract $500 from Karen's goal bonus amount to find how much she makes from the extra $10/point bonus: $600 - $500 = $<<600-500=100>>100
Then divide the extra bonus by the extra rate: $100 / $10/point = <<100/10=10>>10 points
Then add the 10 extra points to the baseline 75 point goal to find the students' average test score: 10 points + 75 points = <<10+75=85>>85 points
Then added the 8 graded tests to the 2 ungraded tests to find the total number of tests: 2 tests + 8 tests = <<2+8=10>>10 tests
Then multiply the 85 point average by the number of tests to find the total number of points the students need to earn: 85 points/test * 10 tests = 850 points
Then multiply the current average by the current number of graded tests to find how many points have been earned so far: 70 points/test * 8 tests = <<70*8=560>>560 points
Then subtract the number of points earned from the number of points needed to find the combine score the last two tests need: 850 points - 560 points = <<850-560=290>>290 points
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Now, solve this next question in the style of the above examples:

Musa is the class teacher of a class of 45 students. He wants to split them into three groups by age. If a third of the class is under 11 years, and two-fifths are above 11 but under 13, how many students will be in the third group (13 years and above)?

### Response:
The first group is a third of the class which is (1/3)*45 = <<1/3*45=15>>15 students
There are 15 students in the first group, so there are 45-15 = <<45-15=30>>30 students
The second group is two-fifths of the class which is (2/5)*45 = <<2/5*45=18>>18 students
There are 18 in the second group so there are 30-18 = <<30-18=12>>12 students left in the third group
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