Marva

H2(g) + I2(g)⇋ 2HI(g)
The system is at equilibrium at a given temperature in a
2 L container. If the system has 0.2 mol of H2, 0.2 mol
of I2, and 0.6 mol of HI at equilibrium; how many moles
of HI should be added to increase the mol number of
H2 to 0.4?
I have solved the question this way
H2 I2 2HI
0.1 0.1 0.3
---- ------ +x
0.3 0.3 -0.6
0.4 0.4 -0.3+x
I found Kc from first equilibrium to be 9
So (x-0.3)^2/(0.4)^2=9 and x is 1.5M to find mole we multiply it by 2 which give as 3 but answer in my book is 1 is my solution correct or not if why where did I go wrong? please help