$A$ bed of roses is shaped as shown in the figure below. In the centre is a square and on each side there is a semi-circle. The side of the square is $21 \, m$. If each rose plant needs $6 \, m^{2}$ of space,then the number of plants in the bed is?

In a triangle $ABC$,$AB + BC = 12 \text{ cm}$,$BC + CA = 14 \text{ cm}$,and $CA + AB = 18 \text{ cm}$. Find the radius of the circle (in $\text{cm}$) which has the same perimeter as the triangle.

The length of a rectangle is twice its breadth. If its length is decreased by $5\, cm$ and breadth is increased by $5\, cm$,the area of the rectangle is increased by $75\, cm^2$. Then the length of the rectangle is......$cm$.

$\Delta ABC$ is similar to $\Delta PQR$. The length of $AB$ is $16 \ cm$ and the length of the corresponding side $PQ$ is $9 \ cm$. If the area of $\Delta ABC$ is $1024 \ cm^2$,what is the area of $\Delta PQR$ 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 $m$)

$A$ rectangular park is $65\, m$ long and $50\, m$ wide. Two cross paths,each $2\, m$ wide,are to be constructed parallel to the sides. If these paths pass through the centre of the rectangle and the cost of construction is ₹ $17.25$ per $m^2$,then find the total cost involved in the construction (in ₹).