Tommy has 70% as many marbles as Henry. If Tommy gives away 20% of the marbles and Henry gives away 50% of his marbles, they will have 265 marbles altogether. How many marbles do the two of them have?

	Tommy	Henry	Total
Comparing Tommy and Henry at first	7x5 = 35 u	10x5 = 50 u
Before	5x7 = 35 u	2x25 =  50 u
Change	- 1x7 = - 7 u	- 1x25 = - 25 u
After	4x7 = 28 u	1x25 = 25 u	265

70% = ⁷⁰₁₀₀ = ⁷₁₀

20% = ²⁰₁₀₀ = ¹₅ 

50% =⁵⁰₁₀₀ = ¹₂ 

The number of marbles that Tommy has at first is repeated.  Make the number of marbles that Tommy has the same.  LCM of 7 and 5 is 35 u.

The number of marbles that Henry has at first is repeated. Make the number of marbles that Henry has the same. LCM of 10 and 2 is 50 u.

Number of marbles in the end
= 28 u + 25 u
= 53 u

53 u = 265

1 u = 265 ÷ 53 = 5

Total number of marbles that the two of them have
= 35 u + 50 u
= 85 u
= 85 x 5
= 425

Answer(s): 425