3b - 7c + 10 + 5c - 2b - 15 + 15 + 12c + b
Arrange the polynomial with like terms together and combine them.
= (3b - 2b + b) + (-7c + 5c + 12c) + (10 - 15 + 15)
= 2b + 10c + 10
Hence, addition of 3b - 7c + 10, 5c - 2b - 15, 15 + 12c + b is 2b + 10c + 10