2n - 1 - -7n + 2 You combine like terms with subtracting
2n - 7n = -5n
-1 - 2 = -3
So -7n + 2 - 2n - 1 = -5n - 3
This isn't really mathematics but I can give you an answer.
Assuming, it's in the dark (cuz in the light, why would you use flash), a person in the photograph can gain a red-eye (in the photo).
The only one I can think of is red eye.
7) 2-3=-1 9) 6-9=-3
11) -3-4=-7 13) -7-6=-13
15)-3-9=-12 17) 6-(-2)=8
19)3-(-5)=8 21) 5-(-8)=13
23)-2-(-1)=-1 25) -10-(-4)=-6
27)-6-(-5)=-1 29) -8-(-6)=-2
31)5-(-3)=8 33) 7-10=-3
35)-2-5=-7 37) -9-(-4)=-5
This looks like the additive inverse property, because when you add something to its negative counterpart (or its additive inverse), you get 0 as a sum.
Another example would be 2+ (-2) = 0. -2 is the additive inverse for 2.
