a: =20,23(15,75+85,25-1)

=20,23*100

=2023

b: =4+4=8

c: =6,48(111-1-10)=648

d: =1,25*8*0,25*4

=10

a. 20,23 x 15,75 + 20,23 x 85,25 - 20,23

 = 20,23 . (15,75 + 85,25 - 1)

= 20,23 . 100

= 2023

b.0,66 + 1,2+ 3,34+2,8 

= 4+4

= 8

c.111 x 6,48 -6,48 - 6,48 x 10

 = 6,48 . (111 - 1 -10)

= 648

d.1,25 x 0,25 x 8 x 4

 = 1,25 . 8 . 0,25 . 4

= 10

\(\text{25 x 20,23 + 105 x 20,23 - 20,25 x 20,23 - 9,75 x 20,23}\\ =20,23\text{ x }\left(25+105-9,75-20,25\right)\\ =20.23\text{ x }100=2023\)

20,23 : 0,2 + 20,23 : 0,25 + 20,23

= 20,23 x 5 + 20,23 x 4 + 20,23 x 1

= 20,23 x (5 + 4 +1)

= 20,23 x 10

= 202,3

Lời giải:
$2,5\times 20,23\times 8\times 5=2,5\times 20,23\times 4\times 2\times 5$

$=(2,5\times 4)\times 20,23\times (2\times 5)$

$=10\times 20,23\times 10=20,23\times 100=2023$

\(x\times\dfrac{1}{4}+x\times75\%=20,23\times90+202,3\)
\(x\times\dfrac{1}{4}+x\times\dfrac{3}{4}=20,23\times90+20,23\times10\)
\(x\times\left(\dfrac{1}{4}+\dfrac{3}{4}\right)=20,23\times\left(90+10\right)\)
\(x\times1=20,23\times100\)
\(x=2023\)

X x 1/4+ X x 75% = 20,23 x 90 +202,3

X x 1/4+ X x 3/4 = 2023

X x ( 1/4 +3/4 ) = 2023

 X x 1 = 2023

x          = 2023

20,23 : 0,25 + 20,23 : 0,1 + 20,23 + 85 x 20,23

= 20,23 x 4 + 20,23 x 10 + 20,23 x 1 + 85 x 20,23

= 20,23 x (4 + 10 + 1 + 85)

= 20,23 x 100

= 2023

 20,23 : 0,25 + 20,23 : 0,1 + 20,23 + 85 x 20,23

= 20,23 x 4 + 20,23 x 10 + 20,23 + 85 x 20,23

= 20,23 x ( 4 + 10 + 1 + 85 )

= 20,23 x 100

= 2023

={7,2x(5,15+3,35)}+{2,8x(4,2+4,3)}
=7,2x8,5+2,8x8,5
=8,5x(7,2+2,8)
=8,5x10
=85

  7,2 x 5,15 + 2,8 x 4,2 + 7,2 x 3,35 + 4,3 x 2,8

= 7,2x ( 5,15 + 3,35 ) + 2,8 x( 4,2 + 4,3 )
= 7,2 x         8,5          +2,8 x        8,5
= 8,5 x ( 7,2 + 2,8 )
= 8,5 x        10
=         85

\(\dfrac{5}{13}\times\dfrac{7}{11}+\dfrac{5}{13}\times\dfrac{2}{11}+\dfrac{8}{13}\times\dfrac{9}{11}\)

\(=\dfrac{5}{13}\times\left(\dfrac{7}{11}+\dfrac{2}{11}\right)+\dfrac{8}{13}\times\dfrac{9}{11}\)

\(=\dfrac{5}{13}\times\dfrac{9}{11}+\dfrac{8}{13}\times\dfrac{9}{11}\)

\(=\dfrac{9}{11}\times\left(\dfrac{5}{13}+\dfrac{8}{13}\right)\)

\(=\dfrac{9}{11}\times1\)

\(=\dfrac{9}{11}\)

a) \(20,23\times21+20,23\times80-20,23\)

\(=20,23\times\left(21+80-1\right)\)

\(=20,23\times100\)

\(=2023\)

\(\dfrac{5}{13}\) \(\times\) \(\dfrac{7}{11}\) + \(\dfrac{5}{13}\) \(\times\) \(\dfrac{2}{11}\) + \(\dfrac{8}{13}\) \(\times\) \(\dfrac{9}{11}\)

= \(\left(\dfrac{5}{13}\times\dfrac{7}{11}+\dfrac{5}{13}\times\dfrac{2}{11}\right)\)+ \(\dfrac{8}{13}\) \(\times\) \(\dfrac{9}{11}\)

= \(\dfrac{5}{13}\)\(\times\) (\(\dfrac{7}{11}\) + \(\dfrac{2}{11}\)) + \(\dfrac{8}{13}\) \(\times\) \(\dfrac{9}{11}\)

= \(\dfrac{5}{13}\) \(\times\) \(\dfrac{9}{11}\) + \(\dfrac{8}{13}\) \(\times\) \(\dfrac{9}{11}\)

= \(\dfrac{9}{11}\) \(\times\)( \(\dfrac{5}{13}\) +\(\dfrac{8}{13}\))

= \(\dfrac{9}{11}\) \(\times\) 1

= \(\dfrac{9}{11}\)

    20,23 \(\times\) 37 - 2,3 \(\times\) 5,5 + 20,23 \(\times\) 63 - 2,3 \(\times\) 4,5

= ( 20,23 \(\times\) 37 + 20,23 \(\times\) 63 ) - ( 2,3 \(\times\) 5,5 + 2,3 \(\times\) 4,5)

= 20,23 \(\times\) ( 37 + 63) - 2,3 \(\times\) ( 5,5 + 4,5)

= 20,23 \(\times\) 100 - 2,3 \(\times\) 10

= 2023 - 23

= 2000