### Class 10 Book Solution from Amitava Mitra in Ratio and Proportion Question No: 2(28)

যদি (a + b + c) p = (b + c - a) q = (c + a - b) r = (a + b - c) s হয়, তবে দেখাও যে,

$\frac{1}{q}+\frac{1}{r}+\frac{1}{s}= \frac{1}{p}$