Answer:
396 
Step-by-step explanation:
Okay, so first we will find the triangle area.
9 * 8 = 72/2 = 36.
Now multiply this by 11 (the width of the prism)
36 * 11 = 396 
No it does not affect the sum because they have the same sign so it wouldn't make a difference
Answer:
E + F = 2c^2 + 5c + 4
Step-by-step explanation:
E=6c^2-2c-1
F=-4c^2+7c+5
E+F= 6c^2 -2c -1 + -4c^2 + 7c + 5
E + F = 6c^2 - 4c^2 - 2c + 7c - 1 + 5
E + F = 2c^2 + 5c + 4