The answer would have to be 52/87. Since it says "given", as in a geometric sense (proof), you know that the overall would have to be 87. It also adds that the students would be in the 10th grade, thus bringing us to the conclusion that 52/87 is correct. Then, simply use a calculator and put in 52/87. You're final answer, rounded to the nearest hundredth, should be 0.60.