Question

please solve this with steps . its emergency

Answer 1

Let the usual speed be =x
Time =distance/speed
Then time taken=1200/x
If speed is increased by 100 km
Then new time=1200/(x+100)
(1200/x)-(1200/(x+100))=1
1200(1/x-1/(x+100))=1
1200((x+100-x)/(x^2+100x))=1
120000=x^2+100x
x^2+100x-120000=0
x^2+400x-300x-120000=0
x(x+400)-300(x+400)=0
(x+400)(x-300)=0
x=-400 or x=300
Speed cannot be negative so
Usual speed =300km/h

Answer 2

hope this help............