Answer
$0.207$
Work Step by Step
$K=[CO_2]^2/[SnO_2][CO]^2$
$K_1=[H_2O]^2/[H_2]^2[SnO_2]$
$K_2=[CO][H_2O]/[CO_2][H_2]$
$\frac 1{K_2^2}\times \frac1{K_1}=\dfrac{[CO_2]^2[H_2]^2}{[CO]^2[H_2O]^2}\dfrac{[H_2O]^2}{[H_2]^2[SnO_2]}=K$
$K=1/(0.771)^2\times1/8.12=0.207$
