It depends on which number has the greatest absolute value.
Think about it as money
If you owe me $10, this is shown as -10
Now if I give you back 2 dollars (+2), How much money do I still owe you.
The equation is -10+2
I still owe you 8 dollars which is portrayed as -8
Hope this helps :)
10 minutes left of homework
1 = 1, 2, 3, 4, 5
4= 4, 8, 12, 16, 20
5= 5, 10, 15, 20, 25