# Question #01d14

Jan 12, 2017

To check your answer substitute the calculated value for the unknown. See explanation.

#### Explanation:

To check if your value is a solution of the given equation you have to substitute the calculated value for the variable and see if left side equals right.

Example 1

Suppose you got $5$ as an answer. If you substitute it you get:

$3 \cdot \textcolor{red}{5} + 5 = 20$

$15 + 5 = 20$

$20 = 20$

Left side equals right so the answer is correct.

Example 2

Now let's suppose that you got $3$ as the answer. If you substitute you get:

$3 \cdot \textcolor{red}{3} + 5 = 20$

$9 + 5 = 20$

$14 = 20$

Left side DOES NOT equal right, so the answer $3$ is incorrect.