We have these points on the graph (0,0) and ( 3, - 2)

The slope is [ -2 - 0 ] / [ 3 - 0 ] = -2/3

So.....using the slope and (0,0).....we have the equation

y = (-2/3) ( x - 0) + 0

y = - (2/3)x multiply through by 3

3y = -2x add 2x to both sides

2x + 3y = 0