Answer: the number of miles must be greater than 200.
Explanation:
Let x represent the number of miles driven with trucks of either company A or company B.
Company A for $140 a day plus $0.40 per mile. This means that the total amount that Company A would charge for x miles in a day is
0.4x + 140
Company B charges $60 a day plus $0.80 per mile to rent the same truck. This means that the total amount that Company B would charge for x miles in a day is
0.8x + 60
For the rental cost for Company A to be less than the rental cost of Company B, the number of miles would be
0.4x + 140 < 0.8x + 60
0.4x - 0.8x < 60 - 140
- 0.4x < - 80
Dividing through by - 4, it becomes
x > - 80/ - 0.4
x > 200