1 ) Lamp posts,dust bins and benches are paced at intervals of 70 m ,56 m ,and 84 m respectively along a strech of road 8km long.At start of the road,lamp post,dust bin and bench are placed together.Only when the three objects are all placed together,they are painted blue.

Question

1 ) Lamp posts,dust bins and benches are paced at intervals of 70 m ,56 m ,and 84 m respectively along a strech of road 8km long.At start of the road,lamp post,dust bin and bench are placed together.Only when the three objects are all placed together,they are painted blue. 
How far away from the start of the road are the second set of the 3 blue object spotted ?

bobpursley · Answer

What is the LCM of the three distances?

MTH · Answer

in the question doesn't write. so , we find the LCM or HCF ?