3/4 . 4/5 + 4/5 . 1/4
= (3/4 + 1/4) . 4/5
= 1 . 4/5
= 4/5
3/4 x 4/5 + 45 x 1/4
\(=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)\times\dfrac{4}{5}=1\times\dfrac{4}{5}=\dfrac{4}{5}\)
\(\dfrac{3}{4}\times\dfrac{4}{5}+\dfrac{4}{5}\times\dfrac{1}{4}=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)\times\dfrac{4}{5}=1\times\dfrac{4}{5}=\dfrac{4}{5}\)