The sum of the interior angles of a triangle is 180°:
180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 60° - 23° = 97°

The first step to solve a quadratic expression that's not set to zero is to solve the equation so that it is set to zero:

y² - y - 17 = -2y - 5
y² - y - 17 + 5 = -2y
y² - y + 2y - 12 = 0
y² + y - 12 = 0

Next, factor the quadratic equation:

y² + y - 12 = 0
(y - 3)(y + 4) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (y - 3) or (y + 4) must equal zero:

If (y - 3) = 0, y must equal 3
If (y + 4) = 0, y must equal -4

So the solution is that y = 3 or -4

To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(2a)(5ab) - (5a²)(7b)
(2 x 5)(a x a x b) - (5 x 7)(a² x b)
(10)(a¹⁺¹ x b) - (35)(a²b)
10a²b - 35a²b
-25a²b

The area of a parallelogram is equal to its length x width:

a = l x w
a = a x b
a = 9 x 2
a = 18

To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(5a)(7ab) + (3a²)(8b)
(5 x 7)(a x a x b) + (3 x 8)(a² x b)
(35)(a¹⁺¹ x b) + (24)(a²b)
35a²b + 24a²b
59a²b