in a triathlon an athlete swims 750m in 15 minutes cycles at an average speed of 40km/h for 30 minutes and runs 5km at an average speed of 3 m/s. find his average speed for the entire competition giving you answer in km/h

Is the product of two rational numbers irrational or rational? first, make a hypothesis by multiplying two rational numbers. then, use variables such as x=a/b and y=c/d and the closure property of integers to prove your hypothesis.