1. **Problem statement:** Simplify the algebraic expressions for waagerecht (horizontal) A and B. 2. **Formula and rules:** Combine like terms by adding or subtracting coefficients of $x$ and constants separately. 3. **Waagerecht A:** $x - 8 + 15 + 2x$ Combine like terms: $$x + 2x = 3x$$ $$-8 + 15 = 7$$ So, $$x - 8 + 15 + 2x = 3x + 7$$ 4. **Waagerecht B:** (Not given, so we skip to C as next) 5. **Waagerecht C:** $7 - 4x - 3 + 7x - 4 + 9x$ Combine like terms: Coefficients of $x$: $$-4x + 7x + 9x = (-4 + 7 + 9)x = 12x$$ Constants: $$7 - 3 - 4 = 0$$ So, $$7 - 4x - 3 + 7x - 4 + 9x = 12x + 0 = 12x$$ **Final answers:** - Waagerecht A: $3x + 7$ - Waagerecht C: $12x$ These match the pattern of the results given in the problem.