First, find 2% of 1200. We do this by multiplying 1200 by .02. This gives us 24. Then, we add 24 to 1200, giving us 1224. (We add 24 since 24 is 2% of 1200, and we're increasing by that 2%)
the line of best fit would be something like in the picture(but straighter)
you would get the equation of it by using y = mx+c
m = the change of y divided by the change of x on the line
c = when the line was on the y axis
put the values in y = mx + c and you have the equation
once you have that just replace x with 100 and rearrange it to equal y and you have the customers