Question 1108177
john is 3 times as old as mary.
the sum of their present ages is 52.
let mary's age be represented by m.
let john's age be represented by j.


the sum of their ages is equal to 52.


the equation for that is j + m = 52


john is 3 times as old as mary.


the equation for that is j = 3m


in the equation of j + m = 52, replace j with 3m to get:


3m + m = 52.


combine like terms to get:


4m = 52.


solve for m to get:


m = 52/4 = 13


since j = 3m, that makes j = 39.


john is currently 39 years old and mary is 13.


they told you to represent mary's age by m, but they didn't tell you what variable to use to represent john's age, so you were free to use any variable name you wanted to.


i chose j.