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 - 13y - 4 = -5y + 5
y² - 13y - 4 - 5 = -5y
y² - 13y + 5y - 9 = 0
y² - 8y - 9 = 0

Next, factor the quadratic equation:

y² - 8y - 9 = 0
(y + 1)(y - 9) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (y + 1) or (y - 9) must equal zero:

If (y + 1) = 0, y must equal -1
If (y - 9) = 0, y must equal 9

So the solution is that y = -1 or 9

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.

8a - 7a = 1a

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

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

a = ½bh
a = ½ x 6 x 3 = \( \frac{18}{2} \) = 9

Angles around a line add up to 180°. Angles around a point add up to 360°. When two lines intersect, adjacent angles are supplementary (they add up to 180°) and angles across from either other are vertical (they're equal).