a,27,42+51,24+22,58-48,76

=(27,42+22,58)+(51,24-48,76)

=50+2,48

=52,48

b,28,67x99+28,67

=28,67x99+28,67x1

=28,67x(99+1)

=28,67x100

=2867

a) 27,42 + 51,24 + 22,58 - 28,76

= 51,24 + 28,76 - 27,42 + 22,58

= 80 - 50 

= 30

b) 28,67 x 99 + 28,67

= 28,67 x 99 + 28,67 x 1 

= 28,67 x ( 99 + 1 )

= 28,67 x 100

= 2867

^ - ^

a,27,42+51,24+22,58-48,76

=(27,42+22,58)+(51,24-48,76)

=50+2,48

=52,48

b,28,67x99+28,67

=28,67x99+28,67x1

=28,67x(99+1)

=28,67x100

=2867

a) 27,42+51,24+22,58-28,76

=27,42+22,58-51,24+28,76

=50+80=130

b) 28,67x99+28,67

=28,67x99+28,67x1

=28,67x(99+1)

=28,67x100=2867

28,67 x 99 + 28,67 

= 28,67 x 99  + 28,67 x 1

= 28,67 x ( 99 + 1 )

= 28,67 x 100

= 2867

28,67 x  99 + 28,67  = 2867

tk mk mk tk lại

tk nha

Tính bằng cách thuạn tiện nhát

28,67 x  99 + 28,67

= 99 x ( 28,67 + 28,67 )

= 99 x 57,34

= 5676,66

Lời giải:
$3,8\times 2+1,9\times 8+7,6\times 2-17,7$

$=1,9\times 2\times 2+1,9\times 8+1,9\times 4\times 2-17,7$

$=1,9\times 4+1,9\times 8+1,9\times 8-17,7$

$=1,9\times (4+8+8)-17,7$

$=1,9\times 20-17,7=38-17,7=20,3$

đề đk ạ

thiếu dấu bn ơi:v

\(99\times36+57\times99+99-84\times99\)

\(=99\times(36+57+1-84)\)

\(=99\times10=990\)

99 x 36 + 57 x 99 - 84 x 99

= 99 x ( 36 + 57 + 1 - 84 )

= 99 x 10

= 990

99 x 36 + 57 x 99 + 99 - 84 x 99

= 99 x ( 36 + 57 + 99 - 84 )

= 99 x 108

= 10.692

Giúp mình với mình đang rất gấp lắm 

99 x 15 + 15 = 15 x ( 99 + 1) = 15 x 100 = 1500

7,48 x ( 99 + 1 )

= 7,48 x 100

= 748

7,48 x ( 99 + 1 )

= 7,48 x 100

= 748

748