Question

One computer can process the income and payroll of a company in 7 hours. A newer computer can process it in 5 hours. Which equation could be used to find how long it will take to process the income and payroll if both computers are used?
a. 1/7 - 1/5 = 1/x
b. 1/x - 1/7 = 1/5
c. 1/7 + 1/x =1/5
d. 1/7 + 1/5 = 1/x

the answer is A?.... or D?
i feel strongly that it is a

Answer 1

It is D

Answer 2

why is that @AwesomeB ?