Question

Consider this equation. 7.8+2(0.75m+0.4)=-6.4m+4(0.5m-0.8) Mia solved the equation and determined that m=2. Is she correct?

A She is incorrect because when substituting 2 for m the result was a true statement.
B She is incorrect because when substituting 2 for m the result was a false statement.
C She is correct because when substituting 2 for m the result was a true statement.
D She is correct because when substituting 2 for m the result was a false statement.

Answer 1

B) She is incorrect because when substituting 2 for m the result was a false statement.

Explanation:

Let's solve it for ourselves and see if Mia is correct:

7.8+2(0.75m+0.4)=-6.4m+4(0.5m-0.8)

7.8+1.5m+0.8=-6.4m+2m-3.2

1.5m+8.6=-4.4m-3.2

8.6=-5.9m-3.2

11.8=-5.9m

-2=m

m=-2

Since the answer is actually m=-2, Mia's guess is incorrect because plugging in m=2 does not make both sides equal. Therefore B is the correct option.