Mary had 80 fliers to post around town. Last week, she posted 1/5 of them. This week, she posted 1/4 of the remaining fliers. How many fliers has she still not posted?
Last week, Mary posted 1/5 of 80, or 16 fliers. There were 80 - 16, or 64 fliers left. This week, Mary posted 1/4 of 64, or 16 fliers. There are 64 - 16, or 48 fliers left.