1. Problem (a): Simplify the expression $4x - 3y + x + 7y$. Step 1: Group like terms. $$4x + x = 5x$$ $$-3y + 7y = 4y$$ Step 2: Write the simplified expression: $$5x + 4y$$ --- 2. Problem (b): Multiply out the expressions. (i) Multiply $5(2 - x)$. Step 1: Distribute 5 to both terms inside the parentheses: $$5 \times 2 = 10$$ $$5 \times (-x) = -5x$$ Step 2: Write the result: $$10 - 5x$$ (ii) Multiply $2x(x + 3)$. Step 1: Use distributive property: $$2x \times x = 2x^2$$ $$2x \times 3 = 6x$$ Step 2: Write the result: $$2x^2 + 6x$$ --- 3. Problem: Calculate the value of $$\frac{3.81 \times 19.8}{2.1}$$ Step 1: Multiply numerator: $$3.81 \times 19.8 = 75.438$$ Step 2: Divide by denominator: $$\frac{75.438}{2.1} = 35.92380952381$$ Step 3: Round to sensible decimal places: $$\approx 35.92$$ --- Final answers: (a) $5x + 4y$ (b.i) $10 - 5x$ (b.ii) $2x^2 + 6x$ (3) $35.92$