John's grill messes up and burns half his steak.  He eats 80% of what isn't burned.  If the steak was originally 30 ounces how much steak did he eat?
There were 30*.5=<<30*.5=15>>15 ounces of unburnt steak
So he ate 15*.8=<<15*.8=12>>12 ounces of steak
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