Question 384103
Start by assigning a letter to represent the unknown quantity.
Let H = the number of hours.
Now write the two equations for the total cost of of the move by each of the two movers.  HL = Heavy lifting and QM = Quick move..
HL = 35H+80
QM = 55H
A) Let H = 2 hours.
HL = 35(2)+80
HL = 70+80
HL = $150
QM = 55(2)
QM = $110 
Quick moves is the better choice for 2 hours work.
B) Let H = 15 hours.
HL = 35(15)+80 You can work this out.
QM = 55(15) This one too.
The smallest answer wins.
C) Here you need to find the value of H in the inequality:
QM < HL so...
55H < 35H+80 Solve fo H. Subtract 35H from both sides.
20H < 80 Divide both sides by 20.
H < 4 hours
Quick move is the better deal for moves less than 4 hours.