I think 4.2 x 10^6 is the answer you're looking for.
Answer:
See explanation
Step-by-step explanation:

Answer:
36 minutes
Step-by-step explanation:
The key is to get the same amount of time for each.
9 * 12 = 108
At 12 minutes per job,
in 108 minutes Alyssa could do
108/12 = 9 jobs
At 9 minutes per job,
Together in 108 minutes they could do
108/9 = 12 jobs
--------------------------
In 108 minutes Mirada does
12 - 9 = 3 jobs
108/3 = 36 minutes per job
Answer:

Step-by-step explanation:
Given
See attachment
Required
The solution
The solution is at the point where the two lines meet.
The lines meet at:
and 
So, the solution is:
