https://tex.z-dn.net/?f=%5Clog_3%5Cdfrac%7B%5Cdfrac%7B72%7D%7B12%7D%7D%7B2%7D%5C%5C%5C%5C%0A%5Clog_3%5Cdfrac%7B72%2A1%7D%7B12%2A2%7D%5C%5C%5C%5C%0A%5Clog_3%5Cdfrac%7B72%2A1%7D%7B24%7D%5C%5C%5C%5C%0A%5Cboxed%7B%5Clog_33+%3D+1%7D