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

7a + x = -5
x = -5 - 7a

then substitute the result (-5 - 7a) into the second equation:

7a - 8(-5 - 7a) = -8
7a + (-8 x -5) + (-8 x -7a) = -8
7a + 40 + 56a = -8
7a + 56a = -8 - 40
63a = -48
a = \( \frac{-48}{63} \)
a = -\(\frac{16}{21}\)

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)(7ab) - (4a²)(2b)
(5 x 7)(a x a x b) - (4 x 2)(a² x b)
(35)(a¹⁺¹ x b) - (8)(a²b)
35a²b - 8a²b
27a²b

A right angle measures 90 degrees and is the intersection of two perpendicular lines. In diagrams, a right angle is indicated by a small box completing a square with the perpendicular lines.

The volume of a cylinder is πr²h:

v = πr²h
v = π(8² x 3)
v = 192π

To solve this equation, isolate the variable for which you are solving (c) on one side of the equation and put everything else on the other side.

-5c - y = -2c - 9y - 8
-5c = -2c - 9y - 8 + y
-5c + 2c = -9y - 8 + y
-3c = -8y - 8
c = \( \frac{-8y - 8}{-3} \)
c = \( \frac{-8y}{-3} \) + \( \frac{-8}{-3} \)
c = 2\(\frac{2}{3}\)y + 2\(\frac{2}{3}\)