Question

Solve the following system using the substitution method.

10x + y = –1
5x + 2y = 16

Answer 1

If you put 5x=16-2y

then you can substitute 10x+y=-1
with
2(5x)+y=-1

and since 5x=16-2y we get:

2(16-2y)+y=-1
32-4y+y=-1
-3y=-33
y=11

When y=11 this gives us:

10x+11=-1
10x=-12
x=-1.2