What is the area of the shaded portion if each side of the square measures $21\,cm$? (in $cm^2$)

Length of a rectangle is twice of its breadth. Area of the rectangle is $18 \, m^2$. What would be its perimeter? (in $m$)

$A$ lawn is in the shape of a rectangle of length $60 \ m$ and width $40 \ m$. Inside the lawn,there is a footpath of uniform width $1 \ m$ bordering the lawn. The area of the path is ....... $m^2$.

$A$ rectangular field costs $Rs. 110$ for levelling at $50$ $paise$ per square metre. If the ratio of length to breadth is $11: 5$, find the length of the field (in $m$).

$2$ small circular parks of diameters $16 \ m$ and $12 \ m$ are to be replaced by a bigger circular park. What would be the radius of this new park,if the new park occupies the same space as the two small parks?

The sides of a triangle are in the ratio of $\frac{1}{2}: \frac{1}{3}: \frac{1}{4}$. If the perimeter is $52 \text{ cm}$,then the length of the smallest side is ........ $\text{cm}$.