for every girl taking classes at the martial arts schools there are 3 boys who are taking classes at the school. if there are 236 students taking classes write and solve a proportion to predict the number of boys taking classes at the school

You have to be very careful how you set this up. For every girl (who counts as 1) there are 3 boys (who count as 3). The total number in the proportion is 3 + 1 = 4. You are given a total, but that is both boys and girls. That's why you need the 4.

3/4 = x / 236 Cross multiply

4x = 3 * 236

4x = 708 Divide by 4

x = 708/4

x = 177

There are 177 boys at the school and 236 - 177 = 59 girls.

there are 78 boys in the class