Altho' I can guess what you have to do here, I'd much prefer that you share the instructions any time you post a problem.
There are several ways in which you could evaluate the given polynomial at x = 1/2. I'm going to use synthetic division for this purpose; if you want some other approach, please say so.
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1/2 / 3 2 -3 5
3/2 7/4 -5/8
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3 7/2 -5/4 4 3/8
Thus, P(1/2) = 4 3/8, or 4.375, or 35/8.