Please see the attachment it is question of equilibrium

In a rxn a+2b gives 2c , 2moles of a ,3 moles of b both, 2 moles of c are placed in 2 L flask and equilibrium concentration of c is 0.5 . The equilibrium constant is??

2-x//2is con of a,3-2x//2is con of b,2plus2x//2is con of c at there equilbrium . Now equating c con to 1//2We get xequal to -0.5 and now using kc formula we get kc equal to0.05