let us use Engineering notation, for the sake of shortening the zeros expression, so 100,000 is just 1E5, namely 1 followed by 5 zeros, and 399 million is just 399E6, or 399 followed by 6 zeros and so on.
[tex]\bf \begin{array}{ccll} deaths&people\\ \cline{1-2} 840800&399E6\\ x&1E5 \end{array}\implies \cfrac{840800}{x}=\cfrac{399E6}{1E5}\implies 840800(1E5)=399E6(x) \\\\\\ \cfrac{840800(1E5)}{399E6}=x\implies \cfrac{84080000000}{399000000}=x\implies 210.73\approx x[/tex]
