Question

Dad's age is equal to the sum of Laura's, Jeri's and Theresa's ages. If Jeri is 4 years older

than Theresa and 3 years younger than Laura, and Dad's age is 38, how old is each
daughter?

Answer 1

Jeri is 13, and thus Theresa is 9 and Laura is 16.

Explanation:

Let's start by declaring variables

D - dad's age

L - laura's age

J - jeri's age

T - theresa's age

The first statement tells us that D = L + J + T

Jeri being 4 years older than Theresa gives us

J = T + 4

Jeri being 3 years younger than Laura gives us

J = L - 3

So notice that the common variable in these two equations is J. So if we can represent every girls age in terms of Jeri's, we will be down to one variable. So

T = J - 4

L = J + 3

Now, we can rewrite the original equation using only J's

38 = (J + 3) + J + (J - 4)

38 = 3J - 1

39 = 3J

13 = J

So Jeri is 13, and thus Theresa is 9 and Laura is 16.