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.

An equation is two expressions separated by an equal sign. The key to solving equations is to repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the equal sign and the answer on the other.

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)(9ab) + (5a²)(4b)
(5 x 9)(a x a x b) + (5 x 4)(a² x b)
(45)(a¹⁺¹ x b) + (20)(a²b)
45a²b + 20a²b
65a²b

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

-7a + x = 3
x = 3 + 7a

then substitute the result (3 - -7a) into the second equation:

7a - 3(3 + 7a) = -9
7a + (-3 x 3) + (-3 x 7a) = -9
7a - 9 - 21a = -9
7a - 21a = -9 + 9
-14a = 0
a = \( \frac{0}{-14} \)
a =

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.)

-6a(a - y)
-6(-5)(-5 + 9)
-6(-5)(4)
(30)(4)
120