Question 48849
it is a problem on time (unitary method)

Reginald does the job in 12 min.
So, his 1 minutes job would be 1/12
Norman does the job in 18 min.
So his 1 minutes job is 1/18
When they both work together,
their 1 min job would be1/12 +1/18 =(18+12)/12*18 =30/12*18 =5/36
So, if both work together they would do the job in 36/5 minutes =7min 12 sec