The ratio is 4:5 meaning out of 9 students 4 are girls and 5 are boys. If there are 36 students, 9 will go into 36 four times so if we multiply each number of the ratio by 4 it gives us the answer.
4:5
4x4 = 16
5x4 = 20
The ratio is 16:20
16 girls to 20 boys... 16 +20 = 36
