It would be 4. Multiply each side by -1/5.
It would cancel out the -1/5 leaving -15 = x.
This is a 30-60-90 right triangle with the shorter leg having a length of 5.
To find the length of x, we must find the length of the longer leg of the right triangle. To do that, we must multiply the shorter leg by the square root of 3.

This is the simplest radical form. Hope this helps! :)
Answer:
3/5
Step-by-step explanation:
cosine is adjacent/hypotenuse
This is just some pythagorean theorem, or a^2 + b^2 = c^2. We have a and b, which is 9 and 12, and we need to find c. To find c, we need to first square those, giving u 81 and 144. Now, we need to add them, giving us 225, meaning c^2 = 225. However, we need to find c on its own, so we have to find the square root of 225. That would be 15.
That is dependent because it is changing.independent stays the same