Problems on H.C.F and L.C.M - General Questions

Find the greatest number that divides 388, 415, 550 leaving the same remainder in each case.

Three bells toll at intervals of 3, 9, 2 minutes. If they toll together now, after how many minutes will they next toll together?

The H.C.F. of two numbers is 20 and their L.C.M. is 840. If one of the numbers is 140, what is the other?

Find the L.C.M. of 11, 35 and 6.

The H.C.F. of two numbers is 7 and their L.C.M. is 588. If one of the numbers is 49, what is the other?