Question 314775
mountains - speed = 35 mph.
let distance in mountains be x
time traveled in mountains = x/35
..
speed on flat land = 85 mph
distance travele = 1200-x miles
time taken on flat land = 1200-x /85
..
Both these times are equal.
x/35 = 1200-x / 85
85x=35(1200-x)
85x =42000 -35x
120x=42000
x= 350 miles distance in the mountains.
On flat land it will travel 1200-350
=850 miles