Third choice is correct hope I helped:3
2x^3 + 9x - 8 - (4x^2 - 15x + 7)....distribute thru the parenthesis
2x^3 + 9x - 8 - 4x^2 + 15x - 7....combine like terms
2x^3 - 4x^2 + 24x - 15 <==
Answer: x=-10, y=13
Step-by-step explanation:

+2y-2y = 0, eliminating y is much easier. So -3x-5x = -8x and 56+24 = 80

Substitute x in any equations but only 1 equation (Don't substitute in both equations.)
For me, I'd substitute x in -3x+2y=50

So the answer is x = -10, y = 13
Chocolate thickshakes will cost $5 and fruit smoothies will cost $3. Let's say the cost of chocolate thickshakes are x and the cost of fruit smoothies are y.
3x + 4y = 27
3x + 3y = 24