What is the y intercept and what does it represent in: y=4+1x

Nnnnneeedd 1.find the residual if you know the actual number is 5.2 and the predicted value is 4.8

Point a is located at (0, 4), and point c is located at (−3, 5). find the x value for the point b that is located one fourth the distance from point a to point c. −0.25 −0.5 −0.75 −1

Amotorboat maintained a constant speed of 12 miles per hour relative to the water in going 45 miles upstream and then returning. the total time for the trip was 8.0 hours. use this information to find the speed of the current.