When tom simplified the expression -2.6 + (-5.4) he got 2.8. What mistake did tom likely make?

Question

Can you also tell how you got the answer

Answer 1

It looks like he added +5.4 to -2.6 when he should have added -5.4, which gives -2.6+5.4 = 2.8.  I got the answer by inspection.

 

The correct answer is -2.6-5.4 = -8

Answer 2

Instead of Tom adding a negative 5.4, he added a positive 5.4.

 

Because 2.6 and 5.4 are both the same sign, he should add them and then take that sign so the answer is -8.0.