Blake mows a half acre of lawn for his grandparents every two weeks. If Blake has already mowed three-fifths of the lawn, how many more square feet must he mow?

Answer: Blake still has to mow 17,424 acres.

There are 43,560 square feet in an acre.

Blake has already mowed 60% of the lawn, leaving him 40% more to mow.

All we have to do is multiply 17,424 by 0.4 to find the number of square feet remaining.

43560 x 0.4 = 17424