Zeph has 70% as many marbles as Vincent. If Zeph gives away 25% of the marbles and Vincent gives away 40% of his marbles, they will have 405 marbles altogether. How many marbles do the two of them have?

	Zeph	Vincent	Total
Comparing Zeph and Vincent at first	7x4 = 28 u	10x4 = 40 u
Before	4x7 = 28 u	5x8 =  40 u
Change	- 1x7 = - 7 u	- 2x8 = - 16 u
After	3x7 = 21 u	3x8 = 24 u	405

70% = ⁷⁰₁₀₀ = ⁷₁₀

25% = ²⁵₁₀₀ = ¹₄ 

40% =⁴⁰₁₀₀ = ²₅ 

The number of marbles that Zeph has at first is repeated.  Make the number of marbles that Zeph has the same.  LCM of 7 and 4 is 28 u.

The number of marbles that Vincent has at first is repeated. Make the number of marbles that Vincent has the same. LCM of 10 and 5 is 40 u.

Number of marbles in the end
= 21 u + 24 u
= 45 u

45 u = 405

1 u = 405 ÷ 45 = 9

Total number of marbles that the two of them have
= 28 u + 40 u
= 68 u
= 68 x 9
= 612

Answer(s): 612