Answer: See explanation
Step-by-step explanation:
We are informed that Stephen rewrites 3r - 18 = 27 as 3(r - 6) = 3(9). This is quite thoughtful of Stephen and it's an easier way to solve the question.
In this case, 3 is a common factor to 3r, 18 and 27. Therefore, we will then have: 3(r - 6) = 3(9).
Since 3 is a common base to both, we are more concerned with the values inside the brackets. This will be:
r-6 = 9
r = 9 + 6
r = 15
Check: 3r - 18
3(15) - 18 = 45 - 18 = 27
