add or subtract the following monomials.

1.)3b+(-7b)
2.)6×+14
3.)-a²+3a²
4.)17v+(-17v)
5.)-21+8k
6.)(-841b)-(-97b)
7.)(9121×)-(826×)
8.)(-174bc)-(526bc)
9.)(-47ײy³z)-(-62ײy³z)
10.)(-206a²b)-(168a²b)​