You can only add or subtract monomials that have the same variable and the same exponent. For example, 2a + 4a = 6a and 4a² - a² = 3a² but 2a + 4b and 7a - 3b cannot be combined. However, you can multiply and divide monomials with unlike terms. For example, 2a x 6b = 12ab.

To solve this equation, 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.

-7a + 2 = \( \frac{a}{-8} \)
-8 x (-7a + 2) = a
(-8 x -7a) + (-8 x 2) = a
56a - 16 = a
56a - 16 - a = 0
56a - a = 16
55a = 16
a = \( \frac{16}{55} \)
a = \(\frac{16}{55}\)

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:

x² - 3x - 16 = -2x + 4
x² - 3x - 16 - 4 = -2x
x² - 3x + 2x - 20 = 0
x² - x - 20 = 0

Next, factor the quadratic equation:

x² - x - 20 = 0
(x + 4)(x - 5) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (x + 4) or (x - 5) must equal zero:

If (x + 4) = 0, x must equal -4
If (x - 5) = 0, x must equal 5

So the solution is that x = -4 or 5

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

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

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

7a + 6(3 - 5a) = -1
7a + (6 x 3) + (6 x -5a) = -1
7a + 18 - 30a = -1
7a - 30a = -1 - 18
-23a = -19
a = \( \frac{-19}{-23} \)
a = \(\frac{19}{23}\)

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

a = l x w
a = a x b
a = 9 x 4
a = 36