\(MSC=12\)
Ta có: \(12:4=3;12:3=4\)
\(\frac{3}{4}=\frac{3\times3}{4\times3}=\frac{9}{12}\)\(;\)\(\frac{2}{3}=\frac{2\times4}{3\times4}=\frac{8}{12}\)
\(\frac{9}{12}+\frac{8}{12}=\frac{17}{12}=1\frac{1}{12}\)
Vậy \(\frac{3}{4}+\frac{2}{3}=1\frac{5}{12}\)

2)  Ta có: \(\hept{\begin{cases}3x=2y;7y=5z\\x-y+z=32\end{cases}\Rightarrow\frac{x}{2}=\frac{y}{3};\frac{y}{5}=\frac{z}{7}\Rightarrow\frac{x}{10}=\frac{y}{15}=\frac{z}{21}.}\)

                                                                                           \(\Rightarrow\frac{x-y+z}{10-15+21}=\frac{32}{16}=2\)

Vậy \(\hept{\begin{cases}x=2.10=20\\y=2.15=30\\z=2.21=42\end{cases}}\)

Ủng hộ nha m.n

em thứ 5 tên là Bi