CHEMISTRY HELP #8 need workings and significant figures please?

2.50 mol of meth is placed in a 3.00L container and heated to 773K so that it becomes a gas. An equilibrium is establishedas it decomposes to produce hydrogen gas and carbon monoxide gas. If the percent reaction of meth is 40.0% calculate the equilibrium concentration of all three species in the system. Then, calculate Keq