There are two friends Nabo and Sona. If Nabo takes 10 days to build a wall and Sona takes 20 days to break the wall.
Find the time taken to build the complete wall when
i) Nabo and Sona are working together.
ii) Nabo and Sona are working on alternate days.

• LCM(10,20)=20 ,1day work for nabo=20/10=2, 1 day work for sona=20/20=1 I) together (2-1)=1 so 20*1= 20
• 7 years agoHelpfull: Yes(0) No(0)
• i) working together
  lcm(10,20)=20
  work for nabo=20/10=2
  work for sona =20/20=1
  working together 20*(2-1)=20 days
  ii)working alternate days
  lcm(10,20)=20
  starting with nabo
  N:day1 wall built=2
  S:day2 wall built=2-1=1
  N:day3 wall built=1+2=3
  S:day4 wall built=3-1=2
  . . . .
  S:day36 wall built= 19-1=18
  N:day37 wall built=18+2=20
  hence 37 days.
  
  
• 7 years agoHelpfull: Yes(0) No(0)