1. **State the problem:** We need to work out three calculations: (a) Multiply 0.3 by 0.02. (b) Find 15% of 40. (c) Calculate 7 minus negative 25. 2. **Formulas and rules:** - Multiplication of decimals: Multiply as whole numbers, then place the decimal point. - Percentage calculation: $\text{Percentage} = \frac{\text{percent}}{100} \times \text{whole}$. - Subtracting a negative number: $a - (-b) = a + b$. 3. **Step-by-step solutions:** **(a) Calculate $0.3 \times 0.02$** Multiply as whole numbers: $3 \times 2 = 6$. Count decimal places: $0.3$ has 1 decimal place, $0.02$ has 2 decimal places, total 3. So, place decimal 3 places from right: $0.006$. **(b) Calculate 15% of 40** Use formula: $15\% \times 40 = \frac{15}{100} \times 40$. Multiply numerator and denominator: $$\frac{15 \times 40}{100} = \frac{600}{100}$$ Simplify fraction by canceling 100: $$\frac{\cancel{600}}{\cancel{100}} = 6$$ So, 15% of 40 is 6. **(c) Calculate $7 - (-25)$** Subtracting a negative is addition: $$7 - (-25) = 7 + 25 = 32$$ 4. **Final answers:** (a) $0.006$ (b) $6$ (c) $32$