They are essentially asking us to solve:

Solving this equation for x tells us that it will take around 80.1 years for the materials in the vault to reduce to 357 pounds.
Time out = d/so = d/523
time back = d/sb = d/415
t = time out + time back
11 = d/523 + d/415 find common deneminator
11 = (415d + 523d)/(523*415)
11*523*415 = 415d + 523d
2387495 = 938d
d = 2545 miles
hope this help
I'll give you a pdf so you can see it yourself and the correct answer is -32b - 32b
Answer:
A
Step-by-step explanation: just divide 71 into 2 which gives you 35.5 making a your answer.