1. Tough Word Problem.

A particular disc can be made to rotate at 2 different speeds. If it were made to rotate slower by 135 revolutions per hour, it would require an additional 2.7-hour to make 315 revolutions. Find the higher speed at which it can operate.

2. Originally Posted by Arka
A particular disc can be made to rotate at 2 different speeds. If it were made to rotate slower by 135 revolutions per hour, it would require an additional 2.7-hour to make 315 revolutions. Find the higher speed at which it can operate.
let $\omega$ be the higher speed of rotation in rev/hr

$t$ = time in hrs to rotate 315 rev at the higher speed

$\omega t = 315$

$(\omega - 135)(t+2.7) = 315$

solve the system of equations for $\omega$ ... I'd start by using the first equation and solving for $t$ in terms of $\omega$, then substitute for $t$ in the second equation.