Efficiency of a rectangular cycle

A monatomic ideal gas goes clockwise through a rectangular cycle in the $(V,p)$ plane formed by two isochoric processes at $3.0\mathrm{L}$ and $6.0\mathrm{L}$ and by two isobaric processes at $1.0\cdot 10^5\mathrm{Pa}$ and $2.0\cdot 10^5\mathrm{Pa}$. Compute the work per cycle and the efficiency.