Given that the number of coins collected per week by two coin-collectors, A and B, are in the ratio 3:4 Let us assume A collects 3c coins per week and B collects 4c coins per week. Total number of coins collected by A in 5 weeks =5*3c=15c, which should be multiple of 7⇒c should be multiple of 7. Total number of coins collected by B in 3 weeks =3⋆4c=12c, which should be a multiple of 24⇒c should be a multiple of 2. So, the least possible value of c is Icm(2,7)=14. Coins sold by A in a week =3c=3⋆14=42.