Hilda has 30% as many stamps as Gillian. Gillian has 140% as many stamps as Vanessa. If Gillian gives 100 stamps to Vanessa, both will then have an equal number of stamps. Find the average number of stamps the three of them have.

Hilda	Gillian	Vanessa
3x7	10x7
	7x10	5x10
21 u	70 u	50 u

30% = ³⁰₁₀₀ = ³₁₀
140% = ¹⁴⁰₁₀₀= ⁷₅

The number of stamps that Hilda has is repeated.  Make the number of stamps that Hilda has the same. LCM of 10 and 7 is 70.

	Gillian	Vanessa	Total
Before	70 u	50 u	120 u
Change	- 10 u	+ 10 u
After	60 u	60 u	120 u

Total number of stamps that Gillian and Vanessa have
= 70 u + 50 u
= 120 u

After Gillian gives to Vanessa, both of them will have the same number of stamps. 

The total number of stamps that Gillian and Vanessa have remains unchanged.

Number of stamps that each of them will have
= 120 u ÷ 2
= 60 u

Number of stamps that Gillian gives to Vanessa
= 70 u - 60 u
= 10 u

10 u = 100

1 u = 100 ÷ 10 = 10

Total number of stamps that three of them have
= 120 u + 21 u
= 141 u

Average number of stamps that each of them have
= 141 u ÷ 3
= 47 u
= 47 x 10
= 470

Answer(s): 470