The first question would be distance from the start, as it is steadily going up as time goes on.
The second question would be distance from the end, as it is steadily going down as time goes on.
The third question would be speed, as the speed is staying stable as shown by the straight lines seen within the distance from start/end graphs being linear lines.
So 2x+12=5x-9
you want all of the unknowns on one side and all of the known values on the other or
subtract 2x from both sides
12=3x-9
add 9 to both sides
21=3x
divide both sides by 3
7=x
It would be A do you need me to explain?
It is right I made this in venn diagram . sorry for poor picture quality