Question

-20 para obter 3 ?

-12 para obter -2

Answer 1

-20 para obter 3 ? 
-20  + x = 3
x = 3 + 20
x = 23
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-12 para obter -2-12 + x = -2
x = -2 + 12
x = 10

Answer 2

-20+20=0
-20+23=3

-12+12=0
-12+10=-2