Elijah, Henry and Clayton collected cards in the ratio of 7 : 8 : 4. After Clayton gave ⁴₅ to Elijah and Henry, Clayton had 390 less cards than Elijah. The number of cards that Henry had increased by 20%. How many cards did Elijah and Clayton have in the end?

	Elijah	Henry	Clayton
Before	7 u	8 u	4 u
Change	+ 1.6 u	+ 1.6 u	- 3.2 u
After	8.6 u	9.6 u	0.8 u

Number of cards that Clayton gave to Elijah and Henry
= ⁴₅ x 4 u
= 3.2 u

Number of cards that Henry received from Clayton
= ²⁰₁₀₀ x 8 u
= 1.6 u

Number of cards that Elijah received from Clayton
= 3.2 u - 1.6 u
= 1.6 u

Number of less cards that Clayton had less than Elijah
= 8.6 u - 0.8 u 
= 7.8 u

7.8 u = 390

1 u = 390 ÷ 7.8 = 50

Number of cards that Elijah and Clayton had
= 8.6 u + 0.8 u
= 9.4 u
= 9.4 x 50
= 470

Answer(s): 470