2+2-8+42

To solve this mathematical expression, we will follow the standard order of operations, which is parentheses first (if any), then multiplication and division (from left to right), and finally addition and subtraction (from left to right). Since this expression contains only addition and subtraction, we'll perform the operations from left to right.

Here is the step-by-step calculation:

2 + 2 - 8 + 42

First, we add 2 and 2: = 4 - 8 + 42

Next, we subtract 8 from 4: = -4 + 42

Finally, we add 42 to -4: = 38

Thus, the result of the expression 2 + 2 - 8 + 42 is 38.