i need help with 2: simplify algebraic expressions

Answer:
a). 11x²
b). 6x + 5y
c). -4x - 20
Step-by-step explanation:
a). 8x² + 3x²
When you collect the like terms (8 and 3 are the coefficients of x²) and add them together, you get 11x²
b). 3x - 5x + y + 4y + 8x
Start by placing the like terms next to each other.
3x - 5x + 8x + y + 4y
Then add/subtract
6x + 5y
c). -4(x + 7) + 8
First, you have to expand the expression and then simplify.
-4x - 28 + 8
-4x - 20