https://tex.z-dn.net/?f=+%5Cdfrac%7B%5Cfrac%7B6%7D7%7D%7B%5Cfrac%7B3%7D4%7D%3D%5Cfrac%7B6%7D7%5Ccdot%5Cfrac%7B4%7D3%3D%5Cfrac+%7B8%7D7