Add the sum of the numbers (-5.4) and (+8.2) to the opposite number of (-2 3/4).

The number are (-5.4) and (+8.2).

Sum of these two numbers are = (-5.4) + (+8.2)

= - 5.4 + 8.2

= 2.8

Now we are going to add this to the opposite number of (-2 3/4).

(-2 3/4) = - 11/4 = - 2.75

now opposite number of - 2.75 is 2.75

Thus,

2.8 + (2.75)

= 2.8 + 2.75

= 5.55