Question

answer hurryyyyyy plzz

Answer 1

let speed be x km/h 
increase by 15
=x+15 
original time - time with increased speed = 1/2 hour 
d=90 km 
d/r = t 
90/x-(90/(x+15)=1/2 
multiply the equation by 2x(x+15) to eliminate the denominator
180(x+15)-180x=x(x+15) 
180x+2700-180x=x^2+15x 
90x cancels off 
x^2+15x-2700=0 
x^2+60x-45x-2700=0 
x(x+60)-45(x+60)=0 
(x+60)(x-45)=0 
x= 45 km/h the original speed. Ignore negative value 
I guess...

Answer 2

the velocity of the train should be 45 kilometre per hour hope this help you