Puzzle 108 - solution

Here was the puzzle. 

Now let us say the restaurant is a at a distance of x miles from start point and y miles from end point. 

From the diagram and Mr. Smith's answers, it is clear that, 

x = distance from start to question 1 point + distance from question 1 point to restaurant

But distance from start to q1 is 1/2 of distance from q1 to restaurant

d1/2+d1 = x

3d1/2 = x

d1 = 2/3 x

If y is the distance from restaurant to end point, then d2  - distance from restaurant to  question2 point is 2/3rd of y

So d2 = 2/3 y

But it is given that d1+d2 = 200

2/3 x + 2/3 y = 200

2/3 (x+y) = 200

x+y = 200 * 3/2 = 300 miles

Total distance from start to end points is 300 miles.