The given expression is

Part A.
We get the first equivalent expression by combining the like terms

We get the second equivalent expression by using the distributive property

Part B.
To show the equivalence between the given expression and one of the part A expressions, we just have to extract the greatest common factor of 24m + 12, which is 4.

Then, we separate the term 6m into m+5m

At last, we use the commutative property

There you have it, the equivalence has been demonstrated.
Part C.
Let's evaluate the expressions when m = 1.


As you can see, using m = 1, we proved that the expressions were equivalent.