Simplify -(-15x)-3x

what do you think? -18x or -12x?

One of these is the answer.

I would have said -30 x^2

it is 30x^2 because 2 negative numbers multiplied become positive.

but there are three :)

To simplify the expression -(-15x) - 3x, we can follow these steps:

Step 1: Distribute the negative sign to the terms inside the parentheses.
-(-15x) = 15x

Step 2: Combine the like terms.
15x - 3x = 12x

Therefore, the simplified expression -(-15x) - 3x is equal to 12x.