So for Avery, we would need to divide 82/98, which will get you (rounded to the thousandths) 0.837. To get from decimal form to percentage form, just move the decimal point 2 spaces to the right. In this case, the percentage is 83.7%
Since Kim has learned 89% of her spelling words while Avery has learned 83.7% of her spelling words, Kim has learned a greater percentage of spelling words than Avery.