Chemical Thermodynamics Part 2

2.2g of nitrous oxide (N2O) gas is cooled at a constant pressure of 1‌atm from 310K to 270K causing the compression of the gas from 217.1‌mL to 167.75‌mL. The change in internal energy of the process, ∆U is ' −x′J. The value of ' x ' is ______[nearest integer]
(Given : atomic mass of N=14gmol−1 and of O=16gmol−1. Molar heat capacity of N2O is 100JK−1mol−1 )