A)2/7:4/5=2/7*5/4=10/28=5/14

b)3/8:9/4=3/8*4/9=12/72=1/6

c)8/21:4/7=8/21*7/4=56/84=2/3

D)5/8:15/8=5/8*8/15=40/120=1/3

k nha

\(\frac{15}{25}=\frac{15:5}{25:5}=\frac{3}{5}\); \(\frac{6}{21}=\frac{6:3}{21:3}=\frac{2}{7}\)

\(\frac{3}{5}+\frac{2}{7}=\frac{31}{35}\)

\(\frac{15}{25}+\frac{6}{21}=\frac{3}{5}+\frac{2}{7}=\frac{21}{35}+\frac{10}{35}=\frac{31}{35}\)

a 1/3 + 5/6 = 7/6

b 2/5 + 3/5 = 1

c 7/8 + 5/8 = 3/2

d 2/7 + 1/6 = 19/42

deo hieu cau tra loi cua kan kan

Câu 1: \(\frac{17}{51}\)x \(\frac{45}{30}\)= \(\frac{1}{3}\)x \(\frac{3}{2}\)

                                   = \(\frac{1}{2}\).

Câu 2: \(\frac{24}{15}\)x \(\frac{56}{72}\)x \(\frac{10}{14}\)= \(\frac{8}{5}\)x \(\frac{7}{9}\)x \(\frac{5}{7}\)

                                                 = \(\frac{56}{45}\)x \(\frac{5}{7}\)

                                                 = \(\frac{8}{9}\)

Câu 3: \(\frac{32}{48}\times\frac{35}{21}\times\frac{63}{14}\times\frac{9}{30}=\frac{2}{3}\times\frac{5}{3}\times\frac{9}{2}\times\frac{3}{10}=\frac{3}{2}\)

k nha

a)17/51x45/40=1/3x3/2=3/6=1/2

b)24/15x56/72x10/14=8/5x7/9x5/7=8/9

c)32/48x35/21x63/14x9/30=2/3x5/3x9/2x3/10=3/2

Đúng 100% nha

con điên

thế nào vậy Lê Trâm Anh?

\(a,\frac{1}{8}+\frac{5}{8}=\frac{1+5}{8}=\frac{6}{8}=\frac{6:2}{8:2}=\frac{3}{4}\)

\(b,\frac{5}{9}+\frac{7}{9}=\frac{5+7}{9}=\frac{12}{9}=\frac{12:3}{9:3}=\frac{4}{3}\)