The second one which is 9.99 + 5n because if you see in the question. Per downloadable. Which means that she can buy more.
For example:
If she buys 2 of the additional downloadable content
It will be 9.99+5(2)
4(x - 3) - 2(x - 1) > 0
4x - 12 - 2x + 2 > 0
2x - 10 > 0 |add 10 to both sides
2x > 10 |divide both sides by 2
x > 10 ⇒ x ∈ (10; ∞)
The fourth option is correct.
E = mgh
m = E/gh
g = E/mh
h = E/mg