this is the question

John bought 3 shirts and 4 pairs of socks for $78.

Joan bought 2 shirts and 6 pairs of socks for $72.

Letting $x equal the price of a shirt and $y equal the price of a pair of socks, write a linear equation to represent each transaction.

Draw on the same axes the graphs of the two equations. Read off the co-ordinates of the point of intersection to find the values of x and y.

i came up with this

3x + 4y = 78

2x+ 6y = 72

howeve, im not sure how do the graphany help on this ould be cool