We have to fill 3 blanks

First is the distance at time 4 second,

Second is time at distance 12 m and the last one is the distance at time 8 second.

The distance at time 4 second: Draw a line from 4 sec (pt A) at x-axis parallel to y-axis mark the point where it intersects the graph (pt B) draw a line parallel to x-axis from pt B and it interest y-axis at pt C. OC represent distance in 4 sec, distance is 8 m.

Similarly, we do for finding time at distance 12 m OD is a time in 12 m, so OC = 6 seconds.

Also for the third part distance in 8 sec, OI represent distance in 8 sec. OI is 16 m. So your table will look like:-