Kathye P. answered • 09/26/12

Math Geek, passionate about teaching

I like to use variables that remind me what they represent, so let's use B for Brian's age and M for Meagan's age. We know that:

B = 48

and

M = 24

What we do not know is how many years we are adding. So the number of years is Y.

So Brian's age plus some number of years equals 3 times Meagan's age plus that number of years. In math terms:

B + Y = 3(M + Y)

You can substitute in their ages:

48 + Y = 3(24 + Y)

To solve it, use distributive property on the right:

48 + Y = 72 + 3Y

Use subtraction to get the Ys on one side and constants on the other:

48 + Y -3Y = 72 +3Y -3Y

gives you: 48 - 2Y = 72

then: 48 -48 - 2Y = 72 -48

so: -2Y = 24

then divide by -2:

-2Y / -2 = 24 / -2

Y = -12

which means that 12 years AGO, Brian was 3 times older than Meagan, when Brian was 36 and Meagan was 12.

Hope this helped!

Kathye

Pam K.

Thank you.

09/26/12