Answer:
$120.
Step-by-step explanation:
The amount he sells the tool kit for = 80 + 20% of 80
= 80 + 16
= $96.
Let m be the marked price, then
m - 0.20m = 96
0.8m = 96
m = $120.
The answer to your question is c
C = 15x + 50
let c be $125 since c represents the cost
15x + 50 = 125
15x = 125 - 50
15x = $75
x = 75 ÷ 15
x = 5