$\frac{p-50}{m-\frac{1}{3}m} = \frac{5}{4}$
$\frac{p-50}{\frac{2}{3}m} = \frac{5}{4}$
$p-50(4) = 5 \frac{2}{3}m$
$4p - 200 = \frac{10}{3}m$
$2p - 100 = \frac{5}{3}m$
$6p - 300 = 5m$
Remember: $p = m$
$6p - 300 = 5p$
$p = 300$
$300 - 50 = \boxed{250}$
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