Yanni's mother gave him $0.40 in addition to $0.85 for a total of $0.40+$0.85 = $<<0.40+0.85=1.25>>1.25.
Yanni found $0.50 so he had a total of $1.25 + $0.50 = $<<1.25+0.5=1.75>>1.75
Therefore, Yanni had $1.75 - $1.6 = $<<1.75-1.6=0.15>>0.15 left
100 cents make $1 so $0.15 is 100*0.15 = <<100*0.15=15>>15 cents
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