The answer is 7 3/4 inches.
I noticed the word "train" in the problem and I knew I had to help you! :)
Answer:
Number of offices to be cleaned to cover the cost of equipment =15
Cost of equipment =$.315 Cost of supplies =$.4 Charge per office =$.25
Number of offices to be cleaned to cover the cost of equipment =x
Then -25x − 4x =315
21x =315
x=315
21=15
Number of offices to be cleaned to cover the cost of equipment =15
Answer: I have no idea
Step-by-step explanation: