428. Someone bought a horse and after some time sold it for 24 pistoles. In this sale, he lost as many percent as the horse cost him. The question is: for what amount did he buy it?
428. If the horse is bought for $x$ pistoles, then he loses $\frac{x^{2}}{100}$ on the sale, hence, $x-\frac{x^{2}}{100}=24$, from which $x_{1}=40$, $x_{2}=60$.