So first you want to multiply everything in the second parenthesis by x.
x(3x+4) = 3x^2 + 4x
Then, you multiply everything in the second parenthesis by -2.
-2(3x+4) = -6x - 8
Take the two products and add them together. Make sure to combine like terms.
3x^2 + 4x - 6x - 8 =
3x^2 - 2x - 8
Hope this helps!
