a. For a scatter plot, just plot the points you see in the table on a graph. The year is x and attendees is y. Some of the coordinates would be (2, 850), (3,925), (4,1000) etc.
b. Once you've graphed all the points. Draw a STRAIGHT line that you think runs through the most points. Select two points from that line, find the slope + y-intercept.
c. Because x is the number of years, plug 10 into your equation and find y :)