contestada

Increasing the average speed of the Pinkerington Express Bus by 13mph resulted in the 260 mile trip taking an hour less than before. What was the original average speed of the bus?

Respuesta :

original speed of the bus = x

Speed increased by 13 mph = x+13

Distance =260 miles

original time = new time +1

Original time - new time = 1

Time = distance / speed

260/x-260/(x+13)=1

LCD = x (x+13)

Multiply:

260 (x+13)-260x = x (x+13)

260x +3380-260x = x^2+13x

x^2+13x-3880 = 0

x^2+65x-52x-3380 =0

x (x+65)-52 (x+65) =0

(x-52) (x+65) =0

Positive: 52

Original speed: 52 mph

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