\(45\text{ × }16-\frac{17}{45}\text{ × }15-18=720-\frac{17}{3}-18=\frac{2089}{3}\)
=\(\frac{45x\left(16-17\right)}{45x\left(15-18\right)}\)
giản ước 45 ta được:\(\frac{16-17}{15-18}=\frac{-1}{-3}=\frac{1}{3}\)
Ta có: \(\frac{45\times16-17}{45\times15-18}=\frac{45-17}{1-18}=\frac{28}{1-18}\)
\(\frac{45\times16-17}{45\times15-18}\)
= \(\frac{45\times\left(15+1\right)-17}{45\times15-18}\)
= \(\frac{45\times15+45-17}{45\times15-18}\)
= \(\frac{45-17}{18}\)
= \(\frac{28}{18}\)
= \(\frac{14}{9}\)
nha
