Human: There are 28 students in a class. Two-sevenths of them were absent last Monday. How many students were present last Monday? Assistant: 
How many students were absent last Monday? ** 28 x 2/7 = <<28*2/7=8>>8 students were absent last Monday.
How many students were present last Monday? ** So, 28 - 8 = <<28-8=20>>20 students were present last Monday.
#### 20