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Question Number 168264 by Mastermind last updated on 07/Apr/22

	Answered by som(math1967) last updated on 07/Apr/22
	$let speed =xkm/hr ∴((240)/(x−4)) −((240)/x)=2 ⇒240{((x−x+4)/(x(x−4)))}=2 ⇒((240×4)/(x^2 −4x))=2 ⇒x^2 −4x−480=0 ⇒x^2 −24x+20x−480=0 ⇒(x−24)(x+20)=0 x=24 speed=24km/hr$
	$l e t s p e e d = x k m / h r$ $∴ \frac{240}{x - 4} - \frac{240}{x} = 2$ $\Rightarrow 240 {\frac{x - x + 4}{x (x - 4)}} = 2$ $\Rightarrow \frac{240 \times 4}{x^{2} - 4 x} = 2$ $\Rightarrow x^{2} - 4 x - 480 = 0$ $\Rightarrow x^{2} - 24 x + 20 x - 480 = 0$ $\Rightarrow (x - 24) (x + 20) = 0$ $x = 24$ $s p e e d = 24 k m / h r$
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