Howard, Henry and Oscar have some erasers. The ratios of their erasers are as follows:

Howard : (Howard + Henry + Oscar) = 1 : 4
Henry : (Howard + Oscar) = 1 : 5

Oscar has 35 erasers more than Henry. In the end, Oscar gives away all he has to Henry and Howard so that both Henry and Howard end up with the same number of erasers, how many erasers has Howard received from Oscar?

Henry	Oscar	Howard	Total
3x3		1x3	4x3
1x2	5x2		6x2
2 u	7 u	3 u	12 u

The total number of erasers is repeated.  Make the total number of erasers the same.  LCM of 4 and 6 is 12.

Number of erasers that Oscar has more than Henry
= 7 u - 2 u
= 5 u

5 u = 35

1 u = 35 ÷ 5 = 7

	Henry	Oscar	Howard
Before	2 u	7 u	3 u
Change	+ 4 u	- 7 u	+ 3 u
After	6 u	0 u	6 u

Number of erasers that Howard has received from Oscar
= 6 u - 3 u 
= 3 u
= 3 x 7
= 21

Answer(s): 21