1. **State the problem:** We have a balance scale with three 3's on one side and three unknown weights represented by square brackets and a circle on the other side. We want to model this as an algebraic equation and solve for the unknowns. 2. **Set up the equation:** Let the square bracket be represented by $x$ and the circle by $y$. Since there are three 3's on one side, their total weight is $3+3+3=9$. On the other side, there are three unknown weights: two square brackets and one circle, so the total weight is $2x + y$. 3. **Write the balance equation:** $$9 = 2x + y$$ 4. **Explain the formula:** The balance scale means both sides are equal in weight, so the sum of weights on the left equals the sum on the right. 5. **Solve for one variable:** We can express $y$ in terms of $x$: $$y = 9 - 2x$$ 6. **Interpretation:** Without additional information, we cannot find unique values for $x$ and $y$, but this equation models the relationship between the weights. 7. **If the problem assumes all weights are equal:** If the square bracket and circle represent the same weight, say $w$, then: $$9 = 3w$$ $$w = \frac{9}{3} = 3$$ So each weight is 3. **Final answer:** The algebraic model is $$9 = 2x + y$$ and the solution depends on additional information. If all weights are equal, each weight is 3.