2. Let $a, b, c, x, y, z$ all be positive numbers, and $a^{2}+b^{2}+c^{2}=25, x^{2}+y^{2}+z^{2}=36, a x+b y+c z=$ 30 , then $\frac{a+b+c}{x+y+z}=$ $\qquad$ .
2. $\frac{5}{6}$ Detailed explanation: According to the Cauchy-Schwarz inequality, let $\frac{a}{x}=\frac{b}{y}=\frac{c}{z}=\frac{a+b+c}{x+y+z}=k$, we get $a^{2}+b^{2}+c^{2}=25=k^{2}\left(x^{2}+y^{2}+\right.$ $\left.z^{2}\right)=36 k^{2}, \therefore \frac{a+b+c}{x+y+z}=k=\frac{5}{6}$.