During a telematch, each group of students was supposed to collect as many coloured marbles as possible. Each colour represented a certain point as tabulated:

Colours	Points
Silver	4
Black	7
Blue	8

In each container, the number of silver marbles was 20% more than the number of blue marbles and 90% less than the number of black marbles. Given that the total possible points if the group managed to collect all the marbles were 3872 points, how many marbles were not silver in colour?

Silver	Black	Blue
6x1		5x1
1x6	10x6
6 u	60 u	5 u

	Silver	Black	Blue	Total
Number	6 u	60 u	5u
Value	4	7	8
Total value	24 u	420 u	40 u	484 u

100% + 20% = 120%
120% = ¹²⁰₁₀₀ =⁶₅

100% - 90% = 10%
10% = ¹⁰₁₀₀ = ¹₁₀

Total number of points collected
= 24 u + 420 u + 40 u
= 484 u

484 u = 3872

1 u = 3872 ÷ 484 = 8

Number of marbles not silver in colour
= 60 u + 5 u
= 65 u
= 65 x 8
= 520

Answer: 520