The sum of an interior angle and its corresponding exterior angle of any polygon is 180^.

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25) Exterior angle of a regular polygon is $72^\circ$. Calculate its interior angle.

Step 1: The sum of an interior angle and its corresponding exterior angle of any polygon is $180^\circ$. $Interior angle + Exterior angle = 180^\circ$

Step 2: Substitute the given exterior angle into the formula. $Interior angle + 72^\circ = 180^\circ$

Step 3: Subtract the exterior angle from $180^\circ$ to find the interior angle. $Interior angle = 180^\circ - 72^\circ = 108^\circ$ The interior angle is $\boxed{*108^\circ*}$

26) Find the Highest Common Factor of numbers 30, 36 and 48.

Step 1: List the factors for each number. • Factors of 30: 1, 2, 3, 5, 6, 10, 15, 30 • Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, 36 • Factors of 48: 1, 2, 3, 4, 6, 8, 12, 16, 24, 48

Step 2: Identify the common factors. The common factors are 1, 2, 3, 6.

Step 3: Determine the highest common factor from the common factors. The highest common factor is 6. The Highest Common Factor is $\boxed{*6*}$

27) Find the value of $x$ in the equation $3(x+1)=9$.

Step 1: Divide both sides of the equation by 3. $\frac{3(x+1)}{3} = \frac{9}{3}$ $x+1 = 3$

Step 2: Subtract 1 from both sides to solve for $x$. $x = 3 - 1$ $x = 2$ The value of $x$ is $\boxed{*2*}$

28) If $\frac{3}{4}$ of the pupils in P6 class are girls, find the number of boys who are in class if there are 48 pupils.

Step 1: Calculate the number of girls in the class. $Number of girls = \frac{3}{4} \times 48$ $Number of girls = 3 \times 12 = 36$

Step 2: Subtract the number of girls from the total number of pupils to find the number of boys. $Number of boys = Total pupils - Number of girls$ $Number of boys = 48 - 36 = 12$ The number of boys in the class is $\boxed{*12*}$

29) A circular garden has a radius of 15 cm. Find its area ($\pi = 3.14$).

Step 1: Recall the formula for the area of a circle. $A = \pi r^2$

Step 2: Substitute the given values for $\pi$ and the radius $r$. $A = 3.14 \times (15 cm)^2$ $A = 3.14 \times 225 cm^2$

Step 3: Calculate the area. $A = 706.5 cm^2$ The area of the circular garden is $\boxed{*706.5 cm^2*}$

30) Find the volume of a cube whose sides are 7 dm. Give the answer in cm$^3$.

Step 1: Convert the side length from decimeters (dm) to centimeters (cm). Since 1 dm = 10 cm, $Side length = 7 dm = 7 \times 10 cm = 70 cm$

Step 2: Recall the formula for the volume of a cube. $V = s^3$

Step 3: Substitute the side length in centimeters into the formula and calculate the volume. $V = (70 cm)^3$ $V = 70 cm \times 70 cm \times 70 cm$ $V = 343000 cm^3$ The volume of the cube is $\boxed{*343000 cm^3*}$

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