All you are trying to do is to find the area inside the curve (the shaded bit). You will then need to apply a correction factor as the axes are not in SI units (a simple x100 I think).
For the first question the shaded area can be found by calculating four simpler areas and then summing them up. I suggest:
Area1 defined by the points (1,0),(3,0),C,D
Area2 defined by the points (1,0),(3,0),A,D
Area3 defined by the points (3,0),(9,0),B,C
Area4 defined by the points (3,0),(9,0),A,B
Two of these areas can be calculated easily because they are rectangles, the other two can be calculated by integrating the equations that you are given over suitable limits.
The total area is then Area1-Area2+Area3-Area4.
The second problem can be done in a very similar way. To do this one you would define six areas and add/subtract them to get the required total.