Question 156327
3h = 110
5h = 160

5h - 3h = 50 becomes

2h = 50

h = 25.

looks like plumber is charging 25 per hour plus a fixed cost.

for 3h job fixed cost = 110 - 75 = 35 dollars.

for 5h job fixed cost = 160 - 125 = 35 dollars.

so fixed cost is 35 dollars plus 25 dollars per hour.

based on that, 8h job should be 35 + (8 * 25) = 235 dollars.