A math problem: triangle square = 2.8 square + circle = 9.2 triangle + circle = triangle + triangle + triangle, then three =? Positive =? Circle=

A math problem: triangle square = 2.8 square + circle = 9.2 triangle + circle = triangle + triangle + triangle, then three =? Positive =? Circle=

Let triangle be x, square be y and circle be Z, then 1) X-Y = 2.82) y + Z = 9.23) x + Z = 3x
According to 3), 4) z = 2x
From 4) we get 5) y = 9.2-z = 9.2-2x
From 5), we get 6) x = 2.8 + y = 2.8 + 9.2-2x, that is 3x = 12 x = 4
So we get x = 4, y = 1.2, z = 8