Substitution.
Here is an example.
Let x be equal to 3 and y equal to 3.

From this we can conclude that the values of both x and y are equal to three therefore x and y have the same value and are equal.

Here in your case we have:

Hope this helps.
r3t40
Answer: 
Step-by-step explanation:
Given
A delivery service charge
for each delivery
and an additional
for each mile traveled
Suppose, x miles are covered
The charge is given by

Therefore, driver traveled 6 miles for delivery
Answer:
no
Step-by-step explanation:
i cant be simplified
Answer:
Credit recovery is a term used to describe a wide variety of educational strategies and programs that give high school students who have failed a class the opportunity to redo coursework or retake a course through alternate means—and thereby avoid failure and earn academic credit.
Step-by-step explanation:
I'm not sure if this help but if it does good luck with it.
A. Natural Numbers
B. Whole Numbers
C. Integers