Problema Solution
A man travelled a distance of 136 km in 8 hrs.some of journey he travelled with speed of 15 km/hr and balance with speed of 18 km/hr.calculate distance which he travelled with speed 18 km/hr?
Answer provided by our tutors
let x be distance with 15 km/h
let y be distance with 18 km/h
These two equations describe the problem:
(8 hours, traveling at 15km/hr and 18km/hr)
x/15 + y/18 = 8
(traveling a total distance of 136 km)
x + y = 136
so x = 136 - y
and we substitute for y in the first equation:
(136 - y)/15 + y/18 = 8
multiply through by 15:
(136 - y) + 15y/18 = 120
(136 - y) + 5y/6 = 120
multiply through by 6:
6(136 - y) + 5y = 720
816 - 6y + 5y = 720
solve for y:
6y - 5y = (816 - 720)
y = 96