Question 1041927
{{{ P = A*e^(-r*t) }}}
{{{ A }}} = amount in dollars before inflation
{{{ P }}} = amount in dollars after inflation
{{{ r }}} = % inflation
{{{ t }}} = time in years of r% inflation
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{{{ r = .038 }}}
{{{ A = 1 }}}
{{{ P = .76 }}}
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{{{ P = A*e^(-r*t) }}}
{{{ .76 = 1*e^(- .038t ) }}}
Take the natural log of both sides
{{{ ln( .76 ) = -.038t }}}
{{{ -.27444 =-.038t }}}
{{{ t = 7.222 }}} 
It will take 7.22 yrs
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check:
{{{ .76 = 1*e^(- .038t ) }}}
{{{ .76 = 1*e^(- .038*7.222 ) }}}
{{{ .76 = e^( -.2744 ) }}}
{{{ .76 = .76003 }}}
close enough