The ratio of tom’s age to mary’s is 3: 4.if tom is 15 how old is mary

Hey there!

Tom's age to Mary's is 3:4; an equivalent ratio is 15:x (x symbolizes Mary's age).

To solve for this, we need to divide our proportions. By that, I mean divide Tom's older age by his younger age. If we do so, we should get a scale factor that we can multiply Mary's younger age by.

15 / 3 = 5

This means that the scale factor of the ages is 5.

x / 4 = 5 (Solving for Mary's unknown age.)

To solve for x, multiply both sides by 4.

x/4 * 4 = x
5 * 4 = 20

x = 20

Mary's age is 20.

I hope this helps!