Plz solve d below bus nd car sum

Dear student

Let the average spped of bus be x km / hr Then, the average speed of car will be (x + 20) km / hr Time taken by bus to cover a distance of 300 km = \frac{300}{x} hrs Time taken by car to cover a distance of 300 km = \frac{300}{x + 20} hrs So, \frac{300}{x} - \frac{300}{x + 20} = 4 \Rightarrow \frac{300 (x + 20) - 300 x}{x (x + 20)} = 4 \Rightarrow 300 x + 6000 - 300 x = 4 x^{2} + 80 x \Rightarrow 4 x^{2} + 80 x - 6000 = 0 \Rightarrow x = \frac{- 80 \pm \sqrt{6400 + 96000}}{8} \Rightarrow x = \frac{- 80 \pm 320}{8} \Rightarrow x = 30 orx = - 50 (not possible) Hence spped of the bus = 30 km / hr and speed of car = 50 km / hr

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