If $x + \frac{1}{x}= 3$ , find the value of $x^3+\frac{1}{x^3}$

A family swimming pool membership costs Tk. 450 per month plus a one-time registration fee of Tk. 350. If a family has paid a total of Tk. 3950, how many months have they been members?

If the average marks of three batches of 55, 60 and 45 students respectively are 50, 55, 60 then the average marks of all the students is :

A person travels from x to y at a speed of 40 km/h and returns by increasing his speed 50%. What is his average speed for both the trips?

Today is Khadija's birthday. After one year, she will become two times as she was ten years ago. What is the current age of Khadija?

If $f\left(x\right)=p{x}^2+qx+r$ and p + q + r = 0 then which one will be factor of f(x) ?

If $y =\frac{1}{x}$, then what will be the constant of variation?