Solving proportions

Question

The ratio of boys to girls on a swimming team is 3 to 4. The team has 49 members. How many are boys ?

Answer 1

This is a proportion problem with a small trick.

4/3 = G/B

Here's the trick

(4/3)+1 = (G/B)+1

(7/3) = (G+B)/B = 49/B =>B=21