A = 2.4
b= 1
C=6.76
is it a right triangle

No

Step-by-step explanation:

All of these statements must be true for it to be a right triangle

2.4 + 1 > 6.76 False

6.76 + 1 > 2.4 True

6.76 + 2.4 > 1 True

This is a very simple but very useful example of dimensional analysis. 
12 hours * 5 dollars / hour means that you can cancel the hours out.
One (hours) is in the numerator.
One (hour) is in the denominator.

The plural singular difference does not matter in mathematics.
12 * 5 dollars = 60 dollars.

60 dollars  <<<<< answer