To multiply binomials, use the FOIL method. FOIL stands for First, Outside, Inside, Last and refers to the position of each term in the parentheses:

(y - 1)(y + 5)
(y x y) + (y x 5) + (-1 x y) + (-1 x 5)
y² + 5y - y - 5
y² + 4y - 5

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

7a - 8a = -1a

The area of a trapezoid is one-half the sum of the lengths of the parallel sides multiplied by the height:

a = ½(b + d)(h)
a = ½(3 + 4)(4)
a = ½(7)(4)
a = ½(28) = \( \frac{28}{2} \)
a = 14

The area of a triangle is equal to ½ base x height:

a = ½bh
a = ½ x 5 x 3 = \( \frac{15}{2} \) = 7\(\frac{1}{2}\)

You need to find the value of c so solve the first equation in terms of y:

-c + y = -9
y = -9 + c

then substitute the result (-9 - -1c) into the second equation:

-7c + 8(-9 + c) = -8
-7c + (8 x -9) + (8 x c) = -8
-7c - 72 + 8c = -8
-7c + 8c = -8 + 72
c = 64
c = \( \frac{64}{1} \)
c = 64