help aider moi c est pour demain

-3 +7 -5 +6 -7 = -3-5-7 +7+6 =-15+13 = -2

(-3) +(-6) -(-2) = -3 -6+2 = -9 +2 = -7

-20  +14 = -6

-10 -( 4-15) = -10 -(-11) = -10+11 = +1