The ratio of hybrid and unhybrid orbitals in benzene molecule is

Benzene molecule has $6s{p}^2$ hybridized carbon atoms. So, no. of hybridized orbitals $=6\times 3=18$.  It has $3\pi$ bonds and 6H atoms which involves pure atomic orbitals. So, pure atomic orbitals $=3\times 2+6=12$

$\therefore$ ratio of hybridized and unhybridized orbitals $=18:12=3:2$