Lower quartile, upper quartile and interquartile range respectively are $\mathrm{Q}_{1}, \mathrm{Q}_{3}$ and $\mathrm{Q}$. If the average of $\mathrm{Q}, \mathrm{Q}_{1}$ and $\mathrm{Q}_{3}$ is 40 and semi-interquartile range is 6, then find the lower quartile.
(1) 24
(2) 36
(3) 48
(4) 60