The simplest formula of the compound containing 32.5% K, 0.839% H, 26.7% Sand 39.9% 0 by mass is

Ratio of atoms $\mathrm{K}:\mathrm{H}:\mathrm{S}:\mathrm{O}::\frac{32.5}{39}:\frac{0.039}{1}:\frac{26.7}{32}:\frac{39.9}{16}::0.833:0.839:0.834:2.494::1:1:1:3$Empirical formula $={\mathrm{KHSO}}_3$