The number '$51$' is divided into two parts such that $\left(\frac{4}{7}\right)$th of the first part is equal to $\left(\frac{5}{4}\right)$th of the second part. then the two parts are

Which of the following equation has the solution $\mathrm{x}=5?$

In a two digit number, the number at ten's place is double of the number at units's place. If we exchange the numbers mutually then the number decreases by $18$, then the number is 

If $-8y-\left(y-5\right)=-13, \text{then} y=$

Solve for $x: \frac{6x^2+13x-4}{2x+5}=\frac{12x^2+5x-2}{4x+3}$

Fifteen years from now, Ravi's age will be four times the age $15$ years ago from now. The present age is