During his tennis career in singles play, john won 3 fewer tournament a titles than tournament b titles, and 2 more tournament c titles than tournament b titles. if he won 17 of these titles total, how many times did he win each one?
how many a titles
how many b titles
how many c titles

Ok use why they told you.

17=A+B+C & A=B-3 &C=2+B
we only what to work with one variable at a time. 
lucky for us we have an idea of what "A" & "C" are. we can plug those into our first equation respectively. 

SOLVE FOR B

17= (B-3)+B+(2+B)
17=B-3+B+2+B
17=3B-1
17+1=3B
18=3B
18/3=B
6=B  (this means he won 6 B titles)

SOLVE FOR A

A=B-3
A=6-3
A=3

SOLVE FOR C

C=2+B
C=2+6
C=8

CHECK

17=A+B+C
17=3+6+8
17=17

The slope of the function is 0.5.