Question : P and Q together complete a job in $4 \frac{2}{5}$ days. R and S complete the same job in $4 \frac{8}{9}$ days. If P, Q, R, and S work together, how many days do they need to complete the same job?

Question : What is the value of $\frac{X}{Y}$ if $\frac{X-5 Y}{X+5 Y}=\frac{7}{13}$

Question : Let $x, y, z$ be fractions such that $x<y<z$. If $z$ is divided by $x$, the result is $\frac{5}{2}$, which exceeds $y$ by $\frac{7}{4}$. If $x+y+z=1 \frac{11}{12}$, then the ratio of $(z-x):(y-x)$ is:

Question : A, B, and C can do a job in 6 days, 12 days and 15 days respectively. After $\frac{1}{8}$th of the work is completed, C leaves the job. The rest of the work is done by A and B together. The time taken to finish the work is:

Question : If $x-\frac{1}{x}=5, x \neq 0$, then what is the value of $\frac{x^6+3 x^3-1}{x^6-8 x^3-1} ?$