Given:
An ideal gas expands at constant pressure:
P = 105 pascals
V1 = 1 m3
V2 = 4 m3
then, the gas is compressed to 1/3 of the pressure and volume 2.50 m3.
Work at constant pressure:
W = PΔV
W = 105 pascals * (4 m3 - 1 m3)
W = 315 Joules
Work at constant volume is zero.