Rosie, this is the solution to the problem, according to the information provided:
Triangles = 1.5 grams
Circles = 2 grams
Squares = x grams
Left string: 4x + 1.5 * 2 + 2 * 2
4x + 3 + 4
4x + 7
Right string: 2x + 1.5 + 3 * 2
2x + 1.5 + 6
2x + 7.5
Rosie, I think we can express this situation rather as an inequality than a equation. Thus:
4x + 7 > 2x + 7.5