Please solve! Brainliest first :D

Answer:
400 miles
Step-by-step explanation:
x - miles driven
140 + 0.70x - a day cost of renting from A
60 + 0.90x - a day cost of renting from B
140 + 0.7x = 60 + 0.9x
- 60 - 60
80 + 0.7x = 0.9x
-0.7x -0.7x
80 = 0.2x
×5 ×5
400 = x