There are 400 students in a local high school. 50 percent are freshmen or sophomores.  1/5 of freshmen and sophomores own a pet.  How many freshmen and sophomores do not own a pet?
Freshman/Sophomores:400(.50)=200 students.
Have pets:200/5=
<gadget id="calculator">200/5</gadget>
<output>40</output>
40 students
200-40=
<gadget id="calculator">200-40</gadget>
<output>160</output>
160 do not have pets.

<result>160</result>