Multiply the cost per hour by number of hours x and for option 1 you need to add the monthly fee:
A) option 1: C= 4x +35
Option2: C = 6.50x
B)
4x+35 < 6.50x
Subtract 4x from both sides:
35 < 2.50x
Divide both sides by 2.50 :
X < 14
You would need to rent more than 14 hours for option 1 to be cheaper.