Alvin wants to know what his average paddling rate was for a canoe trip to a campsite. on the way there it took him 7 hours against a river current of 2 km/hr. on the way back, the same distance took him 5 hours with the same 2 km/hr current. let r= alvin’s average paddling rate. express the rates against the current and with the current in terms of r to complete the below table.