= ( 21 + 29) + ( 23 + 27 )

= 50 + 50

= 100

=(21+29)+(23+27)

=50+50

=100

ai k mình mình k lại cho

21+23+29+27

= (21+29)+(23+27)

= 50+50

= 100

23 x 27 - 46 x 13 = 23 x 27 - 23 x 26

                          = 23 x ( 27 - 26 )

                          = 23 x 1

                          = 23

chúc bạn học tốt !

=23*27-23*2*13.

=23*27-23*26.

=23*(27-26).

=23*1.

=23.

23*27-23*2*13 = 23*27-23*26 = 23*(27-26) = 23*1 = 23

Lời giải:
$=27\times 2+12,44\times 4+17,56\times 4+23\times 2$

$=2\times (27+23)+4\times (12,44+17,56)$

$=2\times 50+4\times 30$

$=100+120=220$

a) = \(\left(\dfrac{2}{7}+\dfrac{4}{7}+\dfrac{1}{7}\right):\dfrac{27}{31}\)

= \(\dfrac{7}{7}\) x \(\dfrac{31}{27}\)

= 1 x \(\dfrac{31}{27}\) = \(\dfrac{31}{27}\)

b) = \(\left(\dfrac{23}{45}:\dfrac{23}{45}\right)\)x \(\dfrac{17}{51}\)

= 1 x \(\dfrac{17}{51}\)= \(\dfrac{17}{51}\)

(450:50) x27=9x27=243

chúc bn hok tốt

(450:50)x27=9x27=243

Chúc bạn làm bài tốt.

(450\(\times\)27):50

=12150:50

=243

(450 x 27) : 50

= (450 : 50) x 27

= 9 x 27

= 243

(45027):50

=(450:5)\(\times\)27

=90\(\times\)27

=2430

(450 x 27) : 50

=(450:50)x27

=9x27

=243

\(\left(450\times27\right):50=\left(450:50\right)\times27=9\times27=243\)

\(\text{( 450 x 27 ) : 50}\)

\(=\text{(450:50) x27}\)

\(\text{=9x27}\)

\(\text{=243}\)

22+23+24+26+27+28

=(22+28)+(23+27)+(24+26)

= 50+50+50

= 150.

                                  HOK TỐT^^