Take a look at this diagram.
The area of the blue region is \(53\) and the area of the orange region is \(125\).
Use this to explain why \[\int_{15}^{30}3f(2x-45)\,dx=67.\]
Now try to evaluate each of the following integrals.
\(\int_{-4}^{-2}\sqrt{x+5}\,dx\)
\(\int_{0.2}^{1.3}e^{2x}\,dx\)
Give some examples of other functions that you can integrate in this way.