Olivia bought 4 smoothies and left a $7 tip. zoe bought 8 smoothies and only left a $2 tip. if they paid the same total amount, each smoothie cost $

8X+2=Y
4X+7=Y

Substitute one problem into the other: 8X+2=4X+7
Get like terms on one side: 8X-4X=7-2 or 4X=5
Get the unknown by itself: 4X/4=5/4 or X=1.25

Now sub what you know back into the original problem: 4•1.25+7=Y
Solve: 4•1.25=5.
5+7=12.
12=Y

Sub Y and X into the first problem: 8•1.25+2=12
Check: 8•1.25=10
10+2=12
12=12.

It solves equally which means we have the right answers so the answer to how much does each smoothie cost is $1.25 :)