$A$ typist uses a sheet measuring $20\, cm \times 30\, cm$ lengthwise. If a margin of $2\, cm$ is left on each side and a $3\, cm$ margin on top and bottom,the percent of the page used for typing is

If the height of an equilateral triangle is $2 \sqrt{3} \text{ cm}$,then the length of its side is ...... $\text{cm}$.

The area of a trapezium is $2500 \, m^2$. One of its parallel sides is $75 \, m$. If the distance between the two parallel sides is $40 \, m$,then find the length of the other parallel side in $m$.

The hypotenuse and the semi-perimeter of a right triangle are $20\, cm$ and $24\, cm$,respectively. The other two sides of the triangle are

$A$ person $A$ takes $15 \text{ seconds}$ to cross a rectangular field diagonally walking at a speed of $52 \text{ m/min}$. $A$ person $B$ takes the same time to cross the same field along its sides (length + width) walking at a speed of $68 \text{ m/min}$. The area of the field is $....... \text{ m}^2$.

If the measures of a diagonal and the area of a rectangle are $25\, cm$ and $168\, cm^2$ respectively,what is the length of the rectangle? (in $cm$)