Answer :
The first step is to try and eliminate one variable.
In this case get rid of y.
+y+-y=0
No you are left with 3x=33 and -x=-17
Add both of them and simplify.
In this case get rid of y.
+y+-y=0
No you are left with 3x=33 and -x=-17
Add both of them and simplify.

Answer:
x= 8
Step-by-step explanation:
step: Substitute−3x+33 for y in x+y=17:
x+y=17
x+−3x+33=17
−2x+33=17(Simplify both sides of the equation)
−2x+33+−33=17+−33(Add -33 to both sides)
−2x=−16