\(\frac{378.132-189.64}{15+18+21+...+45+48}\)
\(=\frac{27.2.7.4.33-7.27.4.2.8}{\left(48+15\right)\times12:2}\)
\(=\frac{27.2.7.4.\left(33-8\right)}{63\times12:2}\)
\(=\frac{3.3.3.2.7.4.25}{3.3.7.2.3}\)
\(=4.25\)
\(=100\)
Dấu "." là dấu nhân
\(\frac{378.132-189.64}{15+18+21+..+45+48}\) =\(\frac{49896-12096}{3.\left(5+6+7+..+15+16\right)}\)
=\(\frac{37800}{3.126}=\frac{37800}{378}=100\)
P/s:Dấu ''.'' = dấu x nha bn