(-15)-(-3) =
(1-7)+(+5) =
(+5) x ( +6 ) =
(+18 ) + ( +6)
(9)+( 8 ) =
(+10)-(+1) =
( +4 ) x ( 3 ) =
( 12 ) + ( +4 ) =
(+6) + (6)
(+11)-(7) =
(-8) x ( +2 ) =
(+15) + ( 3 ) =
(*12 ) + ( 4) =
(8) - ( +2) =
(-7) x ( -5 ) =
(-10 ) = (-2) =