a) They are simply asking you to plot the point on the graph so you'll have to plot (4,2600) om the graph
c)3 and 1/2 means 3.5 years in other words so trace a line going upwards from 3.5 until you meet the graph as soon as the line you traced cuts the graph extend it towards the left to find out the value
hope it helps, please tag this as the brainliest so that it will help many others.
