Henry has 20 Lawns mowed out of a total of 50 lawns. What percentage of the lawns does Henry have to still mow?

Henry has completed 40% of his work, leaving him with a remaining 60%.

What you do is divide 20 by 50 and your answer is .4, move the decimal two places to the right to get your percent, 40. Then subtract it out of 100 and you get the remaining 60%, which essentially is your answer.