Micah was asked to add the following expressions:

First, he combined like terms in the numerator and kept the common denominator
First step is correct. He added the like terms in the numerator, because the denominators are same.

So he got , 
In the next step, he cannot cancel out x^2 from the top and bottom . Because x-4 and 3x+2 are added with x^2
If we have x^2 is multiplied with other terms at the top and bottom , then we can cancel out x^2.
So Micah added the expression incorrectly. Final answer is not correct.
Answer:
H = 20.5 hours
I = 19.5 Hours
Step-by-step explanation:
Start by creating a system.
I = time which the inlet pipe takes alone to fill the pond
H = time which the hose takes alone to fill the pond
10/I + 10/H = 10
H - I = 1
H = 20.5 hours
I = 19.5 Hours
Flower bed A:
circumference= 2 x pi x r= 2x pi x10/2
=10pi feet
Area= pi x r^2=25pi square feet
Flower bed B:
circumference=12 pi feet
Area=36 pi square feet