You have velocity 1 of 5 km per hour after 1 hour and velocity 2 of 3 km per hour after 2 hours.
Part A)
Let Velocity = a +bt, with t being the time in hours.
For velocity 1 you have a +b = 5
For velocity 2, you have a + 2b =3
Now subtract velocity 1 from velocity 2:
a +2b - (a+b) = 3-5
Simplify to get b = -2
Now solve for a in the first equation:
a + b =5
Replace b with -2:
a - 2 = 5
a = 7
Now replace a and b in the original formula:
Velocity = 7 -2t
Part B)
Create a table with x and Y values to graph.
X axis would be the time and the velocity would be the Y axis
Your time would be 0 , 1, 2 3 and 4 hours.
Using the final equation from part A, replace t with the hours ans solve for the velocities, which become the y axis:
7 - 2(0) = 7-0 = 7
7 - 2(1) = 7-2 = 5
7 - 2(2) = 7-4 = 3
7 - 2(3) = 7-6 = 1
7-2(4) = 7-8 = -1
Now you have your x and y coordinates to plot on a graph:
(0,7) (1,5) (2,3) (3,1) and (4,-1)
