Question 430382
Let R=Ruby, S=Sam. The two equations you will use are R=S+3 and R+S=33. Since R is already solved, use the substitution method and place it in the second equation:
(S+3)+S=33
2S+3=33
-3 on both sides
2S=30
Divide by 2 on both sides
S=15

Then, if you place S=15 into either equation, you can solve for R.

R=15+3
R=18

or

R+15=33
-15 on both sides
R=18