Carol drives her daughter to school at an average rate of 30 miles per hour, but only goes an average rate of 20 miles per hour on the way home because of traffic. what is her average rate for the entire trip?
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the answer is not 25 mph, i know for a fact that you can't just add 30 and 20 and divide by 2.

Luke started a weight-loss program. the first week, he lost x pounds. the second week, he lost pounds less than times the pounds he lost the first week. the third week, he lost 1 pound more than of the pounds he lost the first week. liam started a weight-loss program when luke did. the first week, he lost 1 pound less than times the pounds luke lost the first week. the second week, he lost 4 pounds less than times the pounds luke lost the first week. the third week, he lost pound more than times the pounds luke lost the first week.