TeX source:

{\dfrac{3}{4}\left(10y-\dfrac{8}{9}z\right)\left(-\dfrac{8z}{9}+10y\right) = \dfrac{3}{4}\left(10^2y^2-2\cdot 10y\cdot\dfrac{8}{9}z+\left(\dfrac{8}{9}\right)^2z^2\right) = \dfrac{3}{4}\left(100y^2-\dfrac{160}{9}yz+\dfrac{64}{81}z^2\right) = 75y^2-\dfrac{40}{3}yz+\dfrac{16}{27}z^2}