Increase distance speed quickly?

Every day I cover the distance from my house and office at a usual speed and take certain time at the usual speed. When I increase my speed by 5kmph, I take 10 minutes less than usual. If I reduce my speed by 5kmph, I take 15 min more than usual. Find the distance from home to office?

• Answer:

  Let "d" be the distance and "x" be the usual speed. Then according to the question we get the following equations: 1/6 = d/x - d/(x+5) {increase in speed by 5 reduces the time by 10} and 1/4 = d/(x-5) - d/x {decrease in speed by 5 increases the time by 15) Solving these two equations we get: x = 25, d = 25 Km Hence the distance is 25 Km. There you go, fixed it. Thanks for a2a.