Bài 1: 

216,72:4,2=51,6

315:2,5=126

\(a,8,25+4,5\times2,1\\ =8,25+9,45\\ =17,7\\ b,263,24:\left[31,16+34,65\right]-0,71\\ =263,24:65,81-0,71\\ =4-0,71\\ =3,29\\ c,\left[51,24-8,2\right]:26,9:5=43,04:26,9:5\\ =1,6:5\\ =0,32\)

a,8,25 + 4,5 ×2,1

= 8,25 + 9,45

= 17,7

b,263,24 : [31,16 + 34,65] − 0,71

= 263,24 : 65,81 − 0,71

= 4 − 0,71

= 3,29

c, [51,24 − 8,2] : 26,9 : 5

= 43,04 : 26,9 : 5

= 1,6 : 5

= 0,32

\(a,8,25+4,5×2,1\)

\(=8,25+9,45\)

\(=17,7\)

\(=8,25+9,45\)

\(=263,24:65,81−0,71\)

\(=4−0,71\)

\(=3,29\)

\(c,[51,24−8,2]:26,9:5\)

\(=43,04:26,9:5\)

\(=1,6:5\)

\(=0,32\)

x=777

0,32

tích 3 cấy thôi

a)(51,24-8,20):26,9:5

=43.04:26,9:5

=1,6:5

=0,32

b)263,24:(31,16+34,65)-0,71

=263,24:65,81-0,71

=4-0,71

=3,29

tick cho mk nha bạn nhanh lên nhiên