Answer: 3.75 g
Explanation:
Assume the weight of the square is x.
The hanger is in balance so the left side is equal to the right side.
Equation therefore is:
Triangle + Square + 3 * circle = 5* square + circle
3 + x + (3 * 6) = 5x + 6
3 + x + 18 = 5x + 6
5x - x = 3 + 18 - 6
4x = 15
x = 15/4
x = 3.75 g