Answer:
b. Well, I've gotten y=5x+110 for the line of best fit.
To do so, create a line that fits best for a scatter plot. It's best if it's in the middle and hits most coordinates. So y=5x+110 is a good line.
c. To do so, insert 15 into x and solve from there.
y=5(15)+110
y=75+110
y=185
That is the number of people that might attend the reunion on the 15th year.