Grayson rides his bike to the library. His distance in miles from the library after t minutes can be described by the equation d=5−0.3t. Which of the following statements are true for this relationship? Choose all that are true.
a) Grayson's initial distance is 5 miles.
b) Grayson's speed is 0.3 miles per minute.
c) The slope of the graph is -0.3.
d) The y-intercept represents Grayson's starting point.