-(38+24b-c)=-38-24b+с
15b+2(-4b+2a)=15b-8b+4a=7b+4a
24(2b+4c)-2(3c-3b)=48b+96c-6c+6b=90c+54b
2(3b+4c)-(26b-5c)=6b+8c-26b+5c=13c-20b
-17(2a+3b)+2(15a-15)=-34a-51b+30a+30=30-4a-51b
-31(2+3b)-(-60+7)=-62-93b+53=-9-93b
18(2-a)+3(9+2a)=36-18a+27+6a=63-12a