8 triangles. Scale 1 shows that 4 triangles equal 2 circles, so 12 triangles equal 6 circles. Since Scale 2 shows that 6 circles equal 1 square, 12 triangles equal 1 square. 24 triangles, then, equal 2 squares. 2 squares equal 3 diamonds on Scale 3, so 24 triangles equal 3 diamonds. 8 triangles, then, equal 1 diamond and balance Scale 4.
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