A gas goes clockwise round a triangle ABCA on a pressure-volume graph.

In a cycle the gas returns to its start, so $\Delta U = 0$ and the net heat equals the net work. The net work is the area of the loop on a pressure-volume graph: positive for a clockwise loop, negative for an anticlockwise one.

Work done by a gas is the area under its path on a pressure-volume graph. At a steady pressure $W = p\,\Delta V$; along a straight line, the average pressure times $\Delta V$; at a steady temperature $W = nRT\ln\dfrac{V_2}{V_1}$. Expanding gives positive work, squeezing negative. $1\ \text{L} = 10^{-3}\ \text{m}^3$.