Change your problem to :
A railway runs in a loop of 60 km long.
3 companies, A, B and C run trains on the track and plan to build stations.
Company A will build 3 stations at 20 km intervals.
Company B will build 4 stations at 15 km intervals.
Company C will build 5 stations at 12 km intervals.
Will be much easier to "see and handle"; like clock face with 60 minutes...kapish?