Plug in (3,-1) into equations to see:
-1=2-3
-1=-1 CHECK
3-2(-1)=2(3)
3+2=6
5=6 NO
This is not a solution.
Find the LCM (least common multiple) of the denominators, and use that as the denominator for the two fractions.
Ex.

LCM (3, 4) is 12

=
Answer:
84.95 with 15% : 102.87
84.95 with 20% tip: 107.34
125 with 15% tip: 143.75
125 with 20% tip: 150
12.45 with 15% tip: 14.38
12.45 with 20% tip: 14.94
Step-by-step explanation:
Take value on the vertical column and multiply it by either 1.15 or 1.2