Question

The expression -3m - [2m + (5 - m)] + 7 was simplified as 2 - 4m. Without simplifying, explain how you can show that it has been simplified correctly.

Answer 1

You can combine like terms. For this problem, you would combine the m's and the regular numbers. 

Answer 2

Solve the like terms separately

Explanation:

Solve the like terms separately

So, first solve m terms

-3m - 2m + m = -4m

The sign inside the square bracket changes as there is a preceding negative sign. The (5-m) bracket does not matter as you can write the expression as

-3m - [2m + 5 - m] + 7

Then we solve the non m terms

-5 + 7 = 2

So, the expression

-3m - [2m + (5 - m)] + 7 = 2 - 4m