SOLUTION: if r planes can carry p passengers, how many planes are needed to carry m passengers

Since r planes can carry p passengers, m×r planes can carry m×p passengers,
so to carry only m passengers (which is m×p passengers divided by p), we'd
need only (m×r planes divided by p) planes.

Answer  planes:


Or you can do it this way:

r is to p as x is to m



px = mr





x = 


    

Edwin