Question

2.2+x+(-3.4);x=-2.5

Answer 1

2.2 - 2.5 - 3.4
-3.7
.................

Answer 2

The answer is -3.7. Plug in -2.5 into the expression. Then the expression is rewritten as 2.2 - 2.5 - 3.4.  Subtract -2.5 from 2.2 and you get -.3. Now, the expression is -.3 - 3.4. Subtract those from each other and you get -3.7.