=7.15x2+7.15x12-7.15x4

=7.15x(2+12-4)

=7.15x10

=71.5

7,15 : 0,5 + 7,15 * 12 - 7,15 : 25 %

=7,15 : 5/10 + 7,15 * 12 -7,15 : 25/100

=7,15 * 10/5 +7,15 * 12 -7,15 * 25/100

=7,15 * 2  + 7,15 * 12 - 7,15 *4

=7,15 * ( 2+12-4)

=7,15 * 10

=71,,5

\(7,15\div0,5+7,15\times12-7,15\div25\%\)

\(\left(7,15\div0,5-7,15\div25\%\right)+7,15\times12\)

\(\left(7,15\div\frac{1}{2}-7,15\div\frac{1}{4}\right)+7,15\times12\)

\(\left(7,15\times2-7,15\times4\right)+7,15\times12\)

\(7,15\times\left(2-4\right)+7,15\times12\)

\(7,15\times\left(-2\right)+7,15\times12\)

\(7,15\times[\left(-2\right)+12]\)

\(7,15\times10\)

\(71,5\)

17.5 * 4 * 3 * 25

=(4*25)*17,5*3

=100*17,5*3

=1750.3

=5250

    17,5 x 4 x 3 x 25

= ( 4 x 25 ) x 17,5 x 3

=  100 x 17,5 x 3

=  1750 x 3 

=  5250

17,5x4x3x25=(25x4)x17,5x3=(100x17,5)x3=1750x3=5250

Đúng nha bạn!!!@~@

\(\frac{5}{15}+\frac{3}{12}+\frac{4}{20}+\frac{18}{27}+\frac{12}{16}+\frac{30}{25}\)

\(=\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{2}{3}+\frac{3}{4}+\frac{4}{5}\)

\(=\left(\frac{1}{3}+\frac{2}{3}\right)+\left(\frac{1}{4}+\frac{3}{4}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)\)

\(=1+1+1\)

\(=3\)

\(25\times32\times125\times15\\=(25\times4)\times(8\times125)\times15\\=100\times1000\times15\\=100000\times15\\=1500000\)

25 x 32 x 125 x 15 

=(125 x 32 ) x (25 x 15 )

= 4000 x 375

=1 500 000

\(25\times32\times125\times15\)

\(=25\times4\times8\times125\times15\)

\(=\left(25\times4\right)\times\left(8\times125\right)\times15\)

\(=100\times1000\times15\)

\(=\left(1000\times15\right)\times100\)

\(=15000\times100=1500000\)

\(=2345\left(7+13+80\right)+7655\left(24+25+51\right)=10000\cdot100=1000000\)

a: Ta có: \(25+35+76+65+22\)

\(=\left(25+75\right)+\left(35+65\right)+23\)

=223

b: Ta có: \(24+25+24\cdot22\)

\(=24\cdot23+25\)

\(=577\)

\(\left(1-\frac{1}{12}\right).\left(1-\frac{1}{11}\right).\left(1-\frac{1}{10}\right).\left(1-\frac{1}{9}\right).\left(1-\frac{1}{8}\right)\)

\(=\left(\frac{12}{12}-\frac{1}{12}\right).\left(\frac{11}{11}-\frac{1}{11}\right).\left(\frac{10}{10}-\frac{1}{10}\right).\left(\frac{9}{9}-\frac{1}{9}\right).\left(\frac{8}{8}-\frac{1}{8}\right)\)

\(=\frac{11}{12}.\frac{10}{11}.\frac{9}{10}.\frac{8}{9}.\frac{7}{8}\)

\(=\frac{11.10.9.8.7}{12.11.10.8.9}\)

\(=\frac{7}{12}\)

Chúc bạn học tốt !!! 

\(\left(1-\frac{1}{12}\right)\left(1-\frac{1}{11}\right)\left(1-\frac{1}{10}\right)\left(1-\frac{1}{9}\right)\left(1-\frac{1}{8}\right)\)

\(=\frac{11}{12}.\frac{10}{11}.\frac{9}{10}.\frac{8}{9}.\frac{7}{8}\)

\(=\frac{11.10.9.8.7}{12.11.10.9.8}\)

\(=\frac{7}{12}\)

Cảm ơn mọi người nhiều nha