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

Colours	Points
Brown	2
Black	4
Gold	7

In each container, the number of brown beads was 20% more than the number of gold beads and 10% less than the number of black beads. Given that the total possible points if the group managed to collect all the beads were 1989 points, how many beads were not brown in colour?

Brown	Black	Gold
6x3		5x3
9x2	10x2
18 u	20 u	15 u

	Brown	Black	Gold	Total
Number	18 u	20 u	15u
Value	2	4	7
Total value	36 u	80 u	105 u	221 u

100% + 20% = 120%
120% = ¹²⁰₁₀₀ =⁶₅

100% - 10% = 90%
90% = ⁹⁰₁₀₀ = ⁹₁₀

Total number of points collected
= 36 u + 80 u + 105 u
= 221 u

221 u = 1989

1 u = 1989 ÷ 221 = 9

Number of beads not brown in colour
= 20 u + 15 u
= 35 u
= 35 x 9
= 315

Answer: 315