Both computers will do the job in 5 hours and 14 minutes.
Since a computer can process the payroll for Hometel in 10 hours, while an older back up computer needs 11 hours to process payroll, to determine how long would the job take if the two computers are both used to do the job, the following calculation should be performed:
X / 10 + X / 11 = 1
10X + 11X = 110
21X = 110
X = 110/21
X = 5.238
100 = 60
0.238 = X
0.238 x 60/100 = X
0.14 = X
Therefore, both computers will do the job in 5 hours and 14 minutes.
