To solve this equation, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

-4a(a - x)
-4(-7)(-7 - 2)
-4(-7)(-9)
(28)(-9)
-252

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

a = l x w
a = a x b
a = 2 x 3
a = 6

An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite:

d° = b° + c°

To find angle c, remember that the sum of the interior angles of a triangle is 180°:

180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 62° - 54° = 64°

So, d° = 54° + 64° = 118°

A shortcut to get this answer is to remember that angles around a line add up to 180°:

a° + d° = 180°
d° = 180° - a°
d° = 180° - 62° = 118°

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.

9a⁵ - 3a⁵ = 6a⁵

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:

z² + z - 19 = 4z - 1
z² + z - 19 + 1 = 4z
z² + z - 4z - 18 = 0
z² - 3z - 18 = 0

Next, factor the quadratic equation:

z² - 3z - 18 = 0
(z + 3)(z - 6) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (z + 3) or (z - 6) must equal zero:

If (z + 3) = 0, z must equal -3
If (z - 6) = 0, z must equal 6

So the solution is that z = -3 or 6