5 - 5 + 5 - 5 + 5 + 5 +5 - 10

Answer  is 5 

it is just addition but very lengthy

just narrow it down

like 5+5=10

take out the 5+5 from the equation and replace it with a 10

The awnser is 5, 5 & -5 cancel * 2    5+5+5=15    15-10=5