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.)

8b(b - z)
8(-1)(-1 - 1)
8(-1)(-2)
(-8)(-2)
16

The volume of a cube is height x length x width:

v = h x l x w
v = 6 x 3 x 2
v = 36

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) - (2a²)(8b)
(5 x 9)(a x a x b) - (2 x 8)(a² x b)
(45)(a¹⁺¹ x b) - (16)(a²b)
45a²b - 16a²b
29a²b

When solving an equation with two variables, 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.)

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

-3a + x = 5
x = 5 + 3a

then substitute the result (5 - -3a) into the second equation:

9a - 6(5 + 3a) = 7
9a + (-6 x 5) + (-6 x 3a) = 7
9a - 30 - 18a = 7
9a - 18a = 7 + 30
-9a = 37
a = \( \frac{37}{-9} \)
a = -4\(\frac{1}{9}\)