What is the value of $b$ if $5^b + 5^b + 5^b + 5^b + 5^b = 625^{(b-1)}$ ? Express your answer as a common fraction.
$5 * 5^b = 5^(b+1)$
$5^(b+1)$ = $5^(4(b - 1))$
$5^(b+1)$ = $5^[4b - 4]$
$b + 1$ = $4b - 4$
$3b$ = $5$
$b$ = $5/3$
thanks ;)