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.

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(3)(3 - 4)
-4(3)(-1)
(-12)(-1)
12

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° - 64° - 53° = 63°

So, d° = 53° + 63° = 116°

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° - 64° = 116°

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

8c + x = -9
x = -9 - 8c

then substitute the result (-9 - 8c) into the second equation:

-3c - 5(-9 - 8c) = 9
-3c + (-5 x -9) + (-5 x -8c) = 9
-3c + 45 + 40c = 9
-3c + 40c = 9 - 45
37c = -36
c = \( \frac{-36}{37} \)
c = -\(\frac{36}{37}\)

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.

7a x 3b = (7 x 3) (a x b) = 21ab