Answer:
56x² + 3x - 20, which matches given possible answer C
Step-by-step explanation:
Use the "FOIL" method of expanding the product of two binomials (such as you have here):
7x(8x) is the product of the First terms and is 56x²
7x(5) is the product of the Outer terms and is 35x
-4(8x) is the product of the Inner terms and is -32x
-4(5) is the product of the Last terms and is -20
Combining these four products, we get:
56x² + 3x - 20, which matches given possible answer C.
