Question 267051
Three friends jog regularly in a park: Anna jogs every 10 days,
 Barbara jogs every 15 days, and Jo jogs every 14 days.
 One Sunday they happen to jog together.
After how many days will the three friends jog together again? 
:
We know 15 * 14 ends in 0, so will be a multiple of 10
Therefore:
15 * 14 = 210 days together again!