If 3r = 18, what is the value of 6r + 3?

2 ways to do this:

Method 1
If 3r = 18, what is the value of 6r + 3?

A) 6
B) 27
C) 36
D) 39

If we type in the equation 3r = 18 into our search engine, we get:
r = 6

Take r = 6, and subtitute it into 6r + 3:
6(6) + 3
36 + 3
39 or Answer D

Method 2:
6r + 3 = 3r(2) = 3

We're given 3r = 18, so we have:
18(2) + 3
36 + 3
39 or Answer D