Janice notices that the average speed at which she bikes varies inversely with the time it takes her to arrive home from the beach. If it takes her 1 hour and 45 minutes to get home biking at an average speed of 12 km per h, then how long will it take her to get home if she bikes at an average speed of 15 km per h?

He ! a group of farmers planned to clean 80 acres of wheat per day to finish the work on schedule. right before the work started, they received a new piece of machinery that them clean 10 more acres per day than originally planned. as a result of increased productivity in the last day before the deadline they only had to clean 30 acres. how many acres of wheat did the group of farmers have to clean?