Definite integration help

Question

The probem is if integral (upper 12) (lower 2) f(x)dx = 17 and integral (upper 12) (lower 5) f(x)dx = 7, the find the following.

integral(upper 5) (lower(2) f(x)dx

I know the answer is 10, but why is it 10. I can't find an example like this in my textbook so I just wanted more context as to why the answer is 10

Answer 1

The integral is the area under the curve for the first value of "x" (lower limit) to the last value of "x" (upper limit). Like this:

Answer 2

∫₂¹²f(x)dx=∫₂⁵f(x)dx+∫₅¹²f(x)dx

17 = ∫₂⁵f(x)dx + 7

∫₂⁵f(x)dx = 17 - 7 = 10