Explanation: Let the number of members be x, and the original amount contributed by each member be y. Therefore, \(45000/x = y\). Hence, \((x-5) (y+15) = 45000\). \((x-5) [\frac{45000}{x} + 15] = 45000\). \(45000+15x-225000/x-75 = 45000\). \(15x^2-225000-75x = 0\). \(x^{2}-5x-15000=0 \implies x=125\).