Well, you would do 5+3 which is 8. Then divide 160 and 8. The answer is 20. So now multiply 3 and 20. the answer is 60. Now multiply 5 and 20. the answer is 100. 100+60 is 160. So that checks out. As a result, the 5 would be the boys so the 5 and 20 are 100. So there are 100 boys in the grade.
100 boys