Write the Kc expression, set up an ICE chart, substitute, and solve.
moles H2 = 0.763/2.016 and that divided by 3.67 L = M; approximately 0.1 but you need to do it more precisely than that.
moles I2 = 96.9g/molar mass I2 and that divided by 3.67 L = about 0.1 M. Again you should confirm that. It's slight more than that.
moles HI = 90.4/molar mass HI and that divided by 3.67 L for M = about 0.192. Check my numbers.
Then the ICE chart.
initial:
H2 = about 0.1 M
I2 = about 0.1 M
HI = 0
change:
H2 = -x
I2 = -x
HI = +2x
equilibrium:
H2 = 0.1-x
I2 = 0.1-x
HI = 0.192
SO, if HI started out at 0 and it end up at 0.192, then 0.192 must equal to 2x or x = 0.192/2 = 0.096 M
Then H2 at equilibrium must be0.1-0.096 and
I2 must be 0.1-0.096.
Substitute those into Kc expression. and solve for K.
Check my numbers for sure.