[tex]\text{We're trying to find how many stickers she bought}\\\\\text{To find this, we have to calculate her expenses first:}\\\\20-12.85=7.15\\\\\text{To find how many stickers she bought, divide 7.15 by 0.65}\\\\7.15\div0.65=11\\\\\boxed{\text{She bought 11 stickers}}[/tex]