x = y + 30

y = 3z, z=y/3

Therefore, x + y + z = y + 30 + y + y/3 which is equal to 1500.

7y/3 = 1500 - 30 = 1470

y = 1470 x 3/7 = 630

y=630, x=660, z=210.

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Millie has 40 coloured shapes.

25 are circles and the rest are squares

23 of the shapes are blue and the rest are green

Therefore, 25 are circles and 15 are squares.

23 of the shapes are blue, therefore 17 are green.

The least number of blue circles is 8 and the least number of green circles is 2.