Hello, tbenne3!
Did you make a sketch?
Let: .$\displaystyle \int^{0.5}_{4}f(x)\,dx \:=\:4 \qquad \int^{2.5}_{4}f(x)\,dx\;=\;4 \qquad \int^{0.5}_{1}f(x)\,dx \;=\;1 $ These are areas "under" the curve.
With a little thought, we see that the graph looks like this: Code:

.*. 
.*:::::*. 
*::: 4 :::* ..* *.
::::::::::: 1.*:: 1 :*.
  *      *      *    +  *     
4 2.5 *: 1 ::*  0.5
* * 

$\displaystyle \text{Find: }\;\int^{1}_{2.5}f(x)\,dx$
$\displaystyle \text{Find: }\;\int^{2.5}_{1}\bigg[4f(x)  4\bigg]\,dx $
Can you work out these areas now?