Posted by Ann on .
Joe can drive from his house to his office in 40 minutes at an average speed of 40 miles per hour. What average is needed to drive the same distance in half an hour? If necessary, round your answer to the nearest tenth.

Algebra 
PsyDAG,
Distance = Speed/time = 40/(2/3) = ?
?D = Speed/(1/2)
Calculate for distance, then speed.