The coach of a cricket team buys 3 bats and 6 balls for Rs 3900.

Let cost of one bat = Rs. X
Let cost of one ball = Rs. Y
According to the question,

= 3x + 6y = 3900
Dividing equation by  3.
= x + 2y = 1300
= x = 1300 - 2y ..........(i)

Putting y = -1300 , 0 , 1300 we get,

X = 1300 – 2(-1300) = 1300+2600 = 3900
X = 1300 – 2(0) = 1300
X = 1300 – 2(1300) = 1300 – 2600 = -1300
 

She buys another bat and 2 more balls of the same kind for Rs.1300                  (Given)
= x + 2y = 1300 ........(ii)

= x = 1300 - 2y
Putting y = -1300 , 0 , 1300 we get,
X = 1300 – 2(-1300) = 1300+2600 = 3900
X = 1300 – 2(0) = 1300
X = 1300 – 2(1300)  = 1300 – 2600 = -1300

Three solutions of this equation can be written in a table as follows:

Algebric representation:
3x+6y = 3900………………..(i)
X+2y= 1300…………………..(ii)

Graphical Representation for first equation:

Graphical Representation for second equation: