Question

jack is 4 times as old as lacy. 9 years from now the sum of their ages will be 68. how old are they now?

Answer 1

The answer is 12.
since we also know that jack is 2 times lucy now then the entire formula would be 2x - 6 = 18 to solve we add 6 to both sides 2x - 6 + 6 = 18 + 6 the 6s on the left cancel because when you have a positive and negative of the same number it always = 0 we get 2x = 24 then divide both sides by 2 to get the answer 2x / 2 = 24 / 2 the 2s on the left cancel and you get 

Answer 2

J=4L, (J+9)+(L+9)=68  using J=4L in the second equation gives you:

4L+9+L+9=68

5L+18=68

5L=50

L=10 and since J=4L

J=40

So Jack is 40 years old and Lacy is 10 years old.