Question 328280
let brother's speed be xmph
Ortiz's speed = 2x
..
Distance / speed = time
Distance = 350 miles 
brother takes 350/x hours
..
Ortiz takes 350/2x hours
..
350/x-350/2x = 5
LCM =2x
700-350 / 2x = 5
350=2x*5
350=10x
x=35 brother's speed 
Ortiz's speed = 2x = 2*35=70mph