molly is 5 years younger than her sister. The sum of their ages is 37. Define a variable. write an equation and then molly's age.

I will take M as molly and S as her sister

M=x-5

S=x

M+S=37

X-5+x=37

2x-5=37

Now you add 5 on both sides so you get 2x=37+5

-5 on other becomes 0 because when you add + 5 and - 5 get cancels out

So I am left with 2x=37+5

2x=42

Than you divide 2 on both side to get x alone so you are left with

X = (42/2)

X=21

Molly's age equation is x-5

Now you plug x into the equation so you get

21-5

And that's equal to 16

So Molly's age is 16 years