the complete question is
Susan and Steven are cousins. The sum of their ages is 33. The difference between three times Steven's age and half of Susan's age is 36. Find the age of Susan and Steven
let
x-----> Susan's age
y----> Steven's age
we know that
y+x=33-----> equation 1
3y-x/2=36----> multiply by 2----> 6y-x=72----> equation 2
adds equation 1 and equation 2
y+x=33
6y-x=72
-------------+
7y=105--------> y=15
x=33-y----> x=33-15----> x=18
the answer is
Susan's age is 18
Steven's age is 15