Question about integrals (calculus)

∫[1,5] f(x)dx =12 and ∫[4,5] f(x)dx = 3.6
I have to find ∫[1,4] f(x)dx...would it just be 12-3.6 - 8.4?
i know the notation's odd here but its the best i can do. the 1 is the lower limit of integration, and the 5 is the upper limit. not that i am too sure what this all means
thanks for any help

Yes. it would usually be true that
∫[1,4] f(x)dx = ∫[1,5] f(x)dx - ∫[4,5] f(x)dx = 12 - 3.6 = 8.4

Regards - Ian

I think this my have many solutions. It is anyhow difficult to prove that a solution f(x) is the only solution.
f(x)=x give Int f(1,5)= 12. But int f(4,5)=4.5, so this is not the solution.

I do not know how to solve this problem.