45 x ( 13 + 78) + 9 x ( 87 + 22 ) x 5

=  45 x ( 13 + 78) + 45 x ( 87 + 22 ) 

=  45 x ( 13 + 78 + 87 + 22 )

=  45 x                200

=            9000

45 x ( 13 + 78) + 9 x ( 87 + 22 ) x 5

= 45 x 91 + 45 x 109

= 45 x ( 91 + 109 )

= 45 x 200

= 9000

-16877nha

h cho tuiiiiiiiiiiiiiiiiii

\(\left(29+10\right).\left\{450-\left[13.\left(64+4^2\right)\div2\right]\right\}\)

\(=\)\(39.\left\{450-\left[13.\left(64+16\right)\div2\right]\right\}\)

\(=\)\(39.\left\{450-\left[13.80\div2\right]\right\}\)

\(=\)\(39.\left\{450-\left[1040\div2\right]\right\}\)

\(=\)\(39.\left\{450-520\right\}\)

\(=\)\(39.-70\)

\(=\)\(-2730\)

Ta có :

\(\frac{x}{4}=\frac{9}{10}\)

=> 10x = 4 . 9

=> 10x = 36

=> x = 3,6

~~Học tốt~~

a) \(\left(31\frac{6}{13}+5\frac{9}{41}\right)-36\frac{6}{13}\)

\(=\left(31\frac{6}{13}+5\right)+\frac{9}{41}-36\frac{6}{13}\)

\(=36\frac{6}{13}+\frac{9}{41}-36\frac{6}{13}\)

\(=\left(36\frac{6}{13}-36\frac{6}{13}\right)+\frac{9}{41}=\frac{9}{41}\)

b) \(\frac{5}{3}+\frac{-2}{7}-\left(-1,2\right)\)

\(=\frac{35}{21}-\frac{6}{21}+\frac{6}{5}\)

\(=\frac{29}{21}+\frac{6}{5}=\frac{271}{105}\)

c) \(0,25+\frac{3}{5}-\left(\frac{1}{8}-\frac{2}{5}+1\frac{1}{4}\right)\)

\(=\frac{1}{4}+\frac{3}{5}-\frac{1}{8}+\frac{2}{5}-1\frac{1}{4}\)

\(=\left(\frac{1}{4}-1\frac{1}{4}\right)+\left(\frac{3}{5}+\frac{2}{5}\right)-\frac{1}{8}\)

\(=-1+1-\frac{1}{8}=-\frac{1}{8}\)

Thank ^^

ta có : 

\(A=\left(x-\frac{1}{4}\right):\left(\frac{-3}{10}+\frac{7}{12}-\frac{2}{3}\right)=\left(x-\frac{1}{4}\right):\left(\frac{-18}{60}+\frac{35}{60}-\frac{40}{60}\right)=\left(x-\frac{1}{4}\right):\frac{-23}{60}\)

Thay vào ta được:

\(A=\left(\frac{5}{3}-\frac{1}{4}\right):\frac{-23}{60}=\frac{17}{12}:\frac{-23}{60}=\frac{-85}{23}\)