Answer:
15 boys
Step-by-step explanation:
The ratio is 5 : 12
The 12 part of the ratio relates to the students in the class, that is 36
Divide 36 by 12 to find the value of one part of the ratio
36 ÷ 12 = 3 ← value of 1 part of the ratio, thus
5 × 3 = 15 ← number of boys in class