Question

How did the answer come​

Answer 1

Graphical representation of variables enable us to plot the values of a and b

join the known points by a straight line.

when it comes to the point where it coordinate x axis in 2 gives the value of a in correspondence with y axis

Answer 2

When you have drawn the graph and after marking all the points..it is now easier for you to mark the points having variables. Therfore first plot the graph and u will get the answer.