Me solve using substitution method and define variables

Use s for how much Stephanie spent, and b for how much Brittany spent.

s+b=118
s=2b-8

put the value for s in the first equation

(2b-8)+b=118

then combine like terms

3b-8=118

move the -8 over

3b=126

divide by 3

b=42

now put this into the second equation

s=2(42)-8

now simplify

s=84-8
s=76

now check by putting both values in the first equation

42+76=118
118=118

so, Brittany spent $42 and Stephanie spent $76

X=8, y=110 so...  what you do is is have 2 equations: 1. (2x+8)=118
2. x+y=118
then solve for y= ?
subtract 2x+8 on both sides
then you get: y=118-(2x+8)
then put that in the second equation: x+y=118
x+118-(2x+8)=118
add like terms
-x+126=118
subtracts 126 on both sides
-x=-8
divide by negative one
x=8
plug that in the second equation to get y
and you get y=110

x=8, y=110