math
posted by maverick .
Terry bicycles for 1/4 at an average speed of x km/hr. He then cycles for 1/3 hour at an average speed of x+10 km/hr. he cycles a total distance of 15 km. work out the value of x.

(1/4)x + (1/3)(x+10) = 15
(7/12)x = 15  10/3 = 35/3
(1/12)x = 5/3
x = 60/3 = 20