x takes 3 hrs more than y to walk 30 km. but if x doubles his pace he is ahead of y by 1 1/2 hours.find their speed of walking
It may be easier to find the time 1st, but I always like to ZERO IN right away on the answers that're needed.
Let x's and y's speeds be x and y, respectively
We then get the following TIME equation:
xy = 10y - 10x ------ eq (i)
We also get:
xy = - 10y + 20x ------ eq (ii)
2xy = 10x ------ Adding eqs (i) & (ii)
y's speed, or
x(5) = 10(5) - 10x ------ Substituting 5 for y in eq (i)
5x = 50 - 10x
5x + 10x = 50
15x = 50
x's speed, or