Multiply each hourly rate by x ( time to complete the work) add it to the service call for each and then set the equations equal:
50 + 40x = 30 +45x
Subtract 30 from both sides:
20 + 40x = 45x
Subtract 40x from both sides:
20 = 5x
Divide both sides by 5
x = 4
The length is 4 hours.
So,
#1:

Convert to like improper fractions.

Add.

So, one solution could be

.
Another solution could by 9. There is also 10, 11, 12, etc., and all numbers in between.
#2:

Convert into improper fraction form.

Multiply.

Cross-cancel, and we have our final result.

k < 96
96 is not a solution.
95 is a solution.
So is 94, 93, 92, etc, and all numbers in between.
A: Deena subtracted 25, instead of adding it.
B: 9x - 25 = 88.
C: no idea
20 minutes. On brads 4th run and Ty’s 5th run they will be at the beginning at the same time.
the correct answer is 4810 bacteria grew after 9 hours