Find the discriminant of the following quadratic equation: $3x^{2} - 12x + 16 = 0$.

$A$ two-digit number is such that the product of its digits is $10$. When $27$ is added to the original number,the new number obtained is the same as the number obtained by interchanging the digits of the original number. Determine the number.

Solve the following equation using the quadratic formula,if the equation has a solution in $R$: $6x^{2}-5x-1=0$.

Solve the following quadratic equation using the method of factorization: $3x^{2} = -11x - 10$.

Obtain the roots of the following equation using the method of 'completing the square': $3y^{2} + 7y - 20 = 0$.

The speed of a motorboat in still water is $9\,km/h$. In a river,it covers $12\,km$ downstream and the same distance upstream in a total time of $3\,hours$. Find the speed of the current of the river. (The speed of the current of the river is less than the speed of the motorboat in still water.) (in $,km/h$)