You draw two circles and convert the percentages to angles. 100% maps to 360°, to 50% maps to 180 degrees etc.
Then start by drawing a line from the origin of the circle to the top. This is your starting line, work your way clockwise to create pizza slices with the given angles you have just calculated.
In the double-bar graph, you create 5 categories (for each spending) and draw two bars above each category (one for each roommate).
For question b I would categorize the spendings into necessary and unnecessary, and then compare the amount of unnecessary spendings...
