The sum of numbers or expression involves adding the expressions and the numbers together.
Assume that the sum of the degrees is given as:
[tex]Sum = 3 + 4 - 2 + 1[/tex]
The above sum can be rewritten as:
[tex]Sum = 3 + 4 +(- 2) + 1[/tex]
Take the sum of all the numbers (including -2 in bracket)
[tex]Sum = 6[/tex]
If the sum of the degrees is given as [tex]Sum = 3 + 4 - 2 + 1[/tex], then the number of years he worked would be 6
Read more about sum at:
https://brainly.com/question/11562149