First law of thermodynamics

In a thermodynamic process, a gas receives $950\,\text{J}$ of thermal energy and does $620\,\text{J}$ of work on its surroundings. Using the first law of thermodynamics, $\Delta U = Q + W$, where $Q$ is the thermal energy supplied to the gas and $W$ is the work done on the gas, calculate the change in internal energy of the gas.