Question

on tuesday rasheed rode to school from his home at an average speed of 12 km/hr and arrived 5min late .on wednesday he rode to school from his home at an avg speed of 18km /hr and arrived 10min late. how fad does rasheed live from school ?

Answer 1

Let k be the time to get to school on time:
Let x be the distance from school

(distance / speed = time)

x / 12 + k = 5 / 60
and
x / 18 + k = - 10 / 60 ... -> k = - (x / 18 + 1 / 6)

Just came up with an easier way:
x / 12 - x / 18 = 5 / 60 - ( -10 / 60): .....The difference between the two trips.
x / 12 - x / 18 = 1 / 4 .........multiply by 36
3 x - 2 x = 9
x = 9


x / 12 - x / 18 - 1 / 6 = 1 / 12 ..... Multiply by 36
3 x - 2 x - 6 = 3
x = 9