You can put this solution on YOUR website! At present Mohan is 1.5 times as old as Shyam.
M = 1.5S
Six years ago Mohan was three times as old as Shyam.
M - 6 = 3(S - 6)
Replace M with 1.5S (from top equation)
1.5S - 6 = 3(S - 6)
1.5S - 6 = 3S - 18
Collect like terms.
1.5S - 3S = - 18 + 6
-1.5S = - 12
S = 8
Shyam is 8 years old
Mohan is 12 years old.
Hope this helps.
:-)