From Förberedande kurs i matematik 1

A point whose coordinates satisfy \displaystyle y < 3x-4 has a y-coordinate which is less than that of a point lying on the line \displaystyle y=3x-4 and having the same x-coordinate. This means that the area we should shade consists of all points below the line \displaystyle y=3x-4.

We can draw the line \displaystyle y=3x-4 by choosing two x-values, for example \displaystyle x=0 and \displaystyle x=1, using the equation of the line to calculate the corresponding y-coordinates, \displaystyle y=3\cdot 0-4=-4 and \displaystyle y=3\cdot 1-4=-1 respectively, and then draw a straight line between the two points that we have obtained.