Which of the following is a quadratic equation in one variable?

If one of the roots of the quadratic equation $x^{2}+bx-15=0$ is $3$,then the other root is ..... .

If $1$ is the solution of a quadratic equation $3x^{2}-kx+2=0$,then $k=\ldots$

If one of the roots of $2x^{2}-5x+k=0$ is $\frac{7}{2}$,then $k=$ .............

$A$ rectangular park is to be designed whose breadth is $3\, m$ less than its length. Its area is to be $4\, m^2$ more than the area of a park that has already been made in the shape of an isosceles triangle with its base as the breadth of the rectangular park and of altitude $12\, m$ (see Figure). Find its length and breadth.

Find the roots of the following quadratic equation by using the quadratic formula,if they exist: $(x+4)(x+5)=3(x+1)(x+2)+2x$