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

Colours	Points
Grey	4
White	7
Purple	9

In each container, the number of grey marbles was 20% more than the number of purple marbles and 70% less than the number of white marbles. Given that the total possible points if the group managed to collect all the marbles were 836 points, how many marbles were not grey in colour?

Grey	White	Purple
6x1		5x1
3x2	10x2
6 u	20 u	5 u

	Grey	White	Purple	Total
Number	6 u	20 u	5u
Value	4	7	9
Total value	24 u	140 u	45 u	209 u

100% + 20% = 120%
120% = ¹²⁰₁₀₀ =⁶₅

100% - 70% = 30%
30% = ³⁰₁₀₀ = ³₁₀

Total number of points collected
= 24 u + 140 u + 45 u
= 209 u

209 u = 836

1 u = 836 ÷ 209 = 4

Number of marbles not white in colour
= 6 u + 5 u
= 11 u
= 11 x 4
= 44

Answer: 44