Tìm \( x, y, z \) biết: a) \[ \frac{15}{x-9} = \frac{20}{y-12} = \frac{40}{z-24} \quad \text{và} \quad xy = 1200 \] b) \[ \frac{40}{x-30} = \frac{20}{y-15} = \frac{28}{z-21} \quad \text{và} \quad xyz = 22400 \]

----- Nội dung ảnh -----
Bài 6. Tìm \( x, y, z \) biết:

a)
\[
\frac{15}{x-9} = \frac{20}{y-12} = \frac{40}{z-24} \quad \text{và} \quad xy = 1200
\]

b)
\[
\frac{40}{x-30} = \frac{20}{y-15} = \frac{28}{z-21} \quad \text{và} \quad xyz = 22400
\]