a) 11-12+13-14+15-16+17-18+19-20.
=(11-12)+(13-14)+(15-16)+(17-18)+(19-20)
=(-1)+(-1)+(-1)+(-1)+(-1)
=(-1)x5
=-5
b) 101-102-(-103)-104-(-105)-106-(-107)-108-(-109)-110
= 101-102+103-104+105-106+107-108+109-110
=(101-102)+(103-104)+(105-106)+(107-108)+(109-110)
=(-1)+(-1)+(-1)+(-1)+(-1)
=(-1)x5
=-5
a) 11-12+13-14+15-16+17-18+19-20
= (11-12)+(13-14)+(15-16)+(17-18)+(19-20)
= (-1) + (-1) + (-1) + (-1) + (-1)
= (-1) . 5
= -5
b) 101-102-(-103)-104-(-105)-106-(-107)-108-(-109)-110
= 101-102+103-104+105-106+107-108+109-110
= (101-102)+(103-104)+(105-106)+(107-108)+(109-110)
= (-1) + (-1) + (-1) + (-1) + (-1)
= (-1) . 5
= -5
a) 11-12+13-14+15-16+17-18+19-20
= (11-12)+(13-14)+(15-16)+(17-18)+(19-20)
= (-1) + (-1) + (-1) + (-1) + (-1)
= (-1) . 5
= -5
b) 101-102-(-103)-104-(-105)-106-(-107)-108-(-109)-110
= 101-102+103-104+105-106+107-108+109-110
= (101-102)+(103-104)+(105-106)+(107-108)+(109-110)
= (-1) + (-1) + (-1) + (-1) + (-1)
= (-1) . 5
= -5