a) (12 + 8) x 4 = 20 x 4

                         = 80

12 + 8 x 4 = 12 + 32

                         = 44

b) 25 + 75 : 5 = 25 + 15

                         = 40

(25 + 75) : 5 = 100 : 5

                         = 20

a)12/5-4/9x5/6=274/135

b)5/6x9/20:2/3=9/16

c)8/9x7/4+5/12x8/3=8/3

A = 274/135

B = 9/16

C = 8/3

ko đủ bố ai giải được

B

b

b

a) 5 x 8 x 7 = 280

b) 12 + 12 + 12 = 36

a) 5 x 8 x 7

= 40 x 7

= 280

b) 12 + 12 + 12 

= 12 x 3

= 36

a) 280

b) 36

\(a)\frac{5}{12}+\frac{3}{14}+\frac{7}{12}=\left(\frac{5}{12}+\frac{7}{12}\right)+\frac{3}{4}=1+\frac{3}{4}=\frac{7}{4}\)

\(b)\frac{15}{14}\times\frac{17}{18}\times\frac{28}{15}=\frac{15\times17\times28}{14\times18\times15}=\frac{17}{9}\)

\(c)\frac{5}{8}\times\frac{5}{4}+\frac{5}{4}\times\frac{3}{8}=\frac{5}{4}\times\left(\frac{5}{8}+\frac{3}{8}\right)=\frac{5}{4}\times1=\frac{5}{8}\)

\(a)\frac{5}{12}+\frac{3}{14}+\frac{7}{12}=\left(\frac{5}{12}+\frac{7}{12}\right)+\frac{3}{4}=1+\frac{3}{4}=\frac{7}{4}\)

\(b)\frac{15}{14}\times\frac{17}{18}\times\frac{28}{15}=\frac{15\times17\times28}{14\times18\times15}=\frac{17}{9}\)

\(c)\frac{5}{8}\times\frac{5}{4}+\frac{5}{4}\times\frac{3}{8}=\frac{5}{4}\times\left(\frac{5}{8}+\frac{3}{8}\right)=\frac{5}{4}\times1=\frac{5}{8}\)

~Học tốt~

a) x = - 4.

b) x = -5.

a,

b,