imc

Multiplying the numerator and the denominator by the same value does not change the value of the fraction. We can multiply both by $12$, getting $\frac{4-3}{6-4}=\boxed{\frac{1}{2}}$. Alternately, we can directly compute that the numerator is $\frac{1}{12}$, the denominator is $\frac{1}{6}$, and hence their ratio is $\boxed{\frac{1}{2}}$.