What is the height of the flagpole

The graph of f(x), shown below, resembles the graph of g(x) = x2, but it has been changed somewhat. which of the following could be the equation of f(x)?

7. if the value of x varies directly with the value of y, and x = 3 when y = 21. what is the valu y, and x = 3 when y = 21. what is the value of x when y = 105?

What is the answer to this question? i'm a bit stumped. also how do i do it? 5(x - 4) = 2(x + 5)