E = E_0 \exp \left( { - \frac{b}{m}t} \right) = E_0 \exp \left( { - \frac{t}{\tau }} \right)

% MathType!MTEF!2!1!+-
% feaafaart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqr1ngB
% PrgifHhDYfgasaacH8YjY-vipgYlh9vqqj-hEeeu0xXdbba9frFj0-
% OqFfea0dXdd9vqai-hGuQ8kuc9pgc9q8qqaq-dir-f0-yqaiVgFr0x
% fr-xfr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyrai
% abg2da9iaadweadaWgaaWcbaGaaGimaaqabaGcciGGLbGaaiiEaiaa
% cchadaqadaqaaiabgkHiTmaalaaabaGaamOyaaqaaiaad2gaaaGaam
% iDaaGaayjkaiaawMcaaiabg2da9iaadweadaWgaaWcbaGaaGimaaqa
% baGcciGGLbGaaiiEaiaacchadaqadaqaaiabgkHiTmaalaaabaGaam
% iDaaqaaiabes8a0baaaiaawIcacaGLPaaaaaa!4E31!

Pasting the above "text" into MathType 5.0 will enter the above equation and make it possible to edit, save, and use in applications such as MS Word.