How to calculate the yield for an incomplete reaction?
Well the problem doesn't say anything about how to get the % yield. If you start with 0.527 grams of platinum, but have 0.155 grams left, then 0.372 grams reacted.

$\frac{0.372}{0.527} * 100$% = $70.6$%

As for the yield

$\frac{0.372}{0.527} * 0.732 = 0.517$ grams