Explanation:
Combine like terms
a. -8p + (-9p) + (-2p) = -8p -9p -2p = (-8 - 9 - 2)p = -19p
b. -3jk + 5jk + (-6jk) = -3jk + 5jk - 6jk = (-3 + 5 - 6)jk = -4jk
Terms are called "like terms" if they have the same variable part (the same letters in the same powers). Like terms differ at most coefficient.