You do
minutes on tap = n
minutes on ballet = n (same as tap_
minutes on jazz = 2n
n + n+ 2n = 60 minutes
4n= 60 minutes (now divided both sides by 4)
n = 15 minutes 2n = 30 minutes
tap = 15 minutes ballet = 15 minutes and jazz = 30 minutes - Total = 1 hour