
+

equals

.
First, simplify

to

and also

to

. Your problem should look like:

+

.
Second, find the least common denominator of

and

to get 9.
Third, make the denominators the same as the least common denominator (LCD). Your problem should look like:

+

.
Fourth, simplify to get the denominators the same. Your problem should look like:

+

.
Fifth, join the denominators. Your problem should look like:

.
Sixth, simplify. Your problem should look like:

, which is the answer.
7 because the way its set up
Let's consider the scenario after each year:
After the zeroth year, the population is: 120 000(1 + 0.04)⁰
After the first year, the population is: 120 000(1 + 0.04)¹
After the second year, the population is: 120 000(1 + 0.04)²
...
Thus, we can find the general rule:
After the nth year, the population is: 120 000(1 + 0.04)ⁿ
And after the 16th year, the population is 120 000(1 + 0.04)¹⁶ = 224 758 (rounded to nearest whole number)
The answer to this is the top option.
The one on the page with the question.