If ∫acf(x)dx=20\int_a^c f(x) dx = 20∫acf(x)dx=20 and ∫abf(x)dx=8\int_a^b f(x) dx = 8∫abf(x)dx=8, what is ∫bcf(x)dx\int_b^c f(x) dx∫bcf(x)dx?
8
12
20
28