27,56-36-27,57-(-12)=-7,13
1)27,56-36=-(36-27,56)=-8,44
2)-8,44-27,57=-(8,44+27,57)=-19,13
3)-19,13-(-12)=-19,13+12=-(19,13-12)=-7,13
27,56-36-27,56-(-12)=-24
27,56-36-27,57-(-12)=-7,13
1)27,56-36=-(36-27,56)=-8,44
2)-8,44-27,57=-(8,44+27,57)=-19,13
3)-19,13-(-12)=-19,13+12=-(19,13-12)=-7,13
27,56-36-27,56-(-12)=-24