a: =(21-11)+(22-12)+(23-13)+(24-14)
=10+10+10+10
=40
b: =(34-14)+(35-15)+(36-16)+(37-17)
=20+20+20+20
=80
a, =(21-11)+(22-12)+(23-13)+(24-14)
=10+10+10+10
=40
b. =(34-14)+(35-15)+(36-16)+(37-17)
=20+20+20+20
=80
c,55+56+57+58-35-36-37-38
=111+57+58-35-36-37-38
=168+58-35-36-37-38
=226-35-36-37-38
=191-36-37-38
=155-37-38
=118-38
=80