Question 2:

City: y=9.50+2.8484x?

County: y = 6.76+2.32x x.

Rural areas: y =1.80+0.42x.

The coefficient of x represents the slope of the linear equation in the graph. Looking at the three straight lines in the picture, we can see that 0.42 (that is, the slope of the straight line in rural areas) means that the annual enrollment in rural areas is the slowest.

Question 3: As can be seen from the same picture, at this stage, the rate of college entrance examination in cities has the fastest annual growth.