The table shows the number of miles people in the U. S. traveled by car annually from 1975 to 2015. The equation for the line of best fit is y=0.048x​+1.345, where x is the number of years since 1975 and y is the number of​ vehicle-miles traveled in trillions. What do the slope and​ y-intercept represent? Estimate the number of miles people in the U. S. traveled in 2007. What is a reasonable prediction for the number of miles people in the U. S. will travel in​ 2022? Year ​Vehicle-Miles Traveled in U. S.​ (in trillions): 1975 1.298 1980 1.529 1985 1.720 1990 2.118 1995 2.387 2000 2.697 2005 2.973 2010 2.945 2015 3.055 What does the slope​ represent? Select the correct choice below and fill in the answer​ box(es) to complete your choice. ​(Type an integer or a​ decimal.)