Efetue as calculas:
[tex]( + 16) + ( + 31) = [/tex]
[tex]( - 12) + ( + 20 = [/tex]
[tex]( + 26) + ( - 15) = [/tex]
[tex] ( + 9) + ( - 11) = [/tex]
[tex]( - 36) + ( + 25) = [/tex]
[tex]( + 9) + ( - 28) = [/tex]
