24/y=3/5*8/3
24/y=8/5
24:y=8/5
y=24;8/5
y=15
b,42/25:y/5=6/7
y/5=42/25:6/7
y/5=49/25
y:5=49/25
y=49/25*5
y=49/5=9,8
\(\frac{24}{y}:\frac{8}{3}=\frac{3}{5}\)
\(\Rightarrow\frac{24}{y}=\frac{3}{5}\times\frac{8}{3}\)
\(\Rightarrow\frac{24}{y}=\frac{8}{5}\)
\(\Rightarrow y=\frac{8}{5}\times24=\frac{192}{5}\)
b , \(\frac{42}{25}:\frac{y}{5}=\frac{6}{7}\)
\(\Rightarrow\frac{y}{5}=\frac{6}{7}\times\frac{42}{25}=\frac{36}{25}\)
\(\Rightarrow y=\frac{36}{25}\times5=\frac{36}{5}\)
\(\frac{24}{y}:\frac{8}{3}=\frac{3}{5}\) \(\frac{42}{25}:\frac{y}{5}=\frac{6}{7}\)
\(\frac{24}{y}=\frac{3}{5}\cdot\frac{8}{3}\) \(\frac{y}{5}=\frac{42}{25}:\frac{6}{7}\)
\(\frac{24}{y}=\frac{8}{5}\) \(\frac{y}{5}=\frac{42}{25}\cdot\frac{7}{6}\)
\(\Rightarrow8y=24\cdot5\) \(\frac{y}{5}=\frac{49}{25}\)
\(8y=120\) \(\Rightarrow25y=5\cdot49\)
\(y=15\) \(25y=245\)
\(y=\frac{49}{5}\)
Chia phân số: phân số thứ nhất nhân với phân số thứ hai đảo ngược
VD: 3/5 : 1/2 = 3/5 x 2/1 = 3/5 x 2 = 6/5