Question

How do I solve the following by using substitution? Y=4x+9 10x=18 -2y

Answer 1

Plug 4x=9 in for y:
10x=18-2(4x+9)
10x=18-8x-18
10x=-8x
18x=0
x=0

now plug 0 in for x:
y=4(0)+9
y=9

to check, plug x and y back into one of the equations to make sure they are right:

10(0)=18-2(9)
0=18-2*9
0=18-18
0=0