Question

a train covers a distance of 90 km at a uniform speed had the speed been 15 km per hour more it would have taken 30 minutes less for the journey find the original speed of the train

Answer 1

(1/2) = (90/X) -(90/(X+15))

1/180 = 15 / (x^2 +15x)
x^2 +15x = 180*15
solving this equation
X = 27.94 km/h.

thanks for asking.