The places are arranged as below:
|<---------------d=(3a)----------------->|
Harbor_____d=(b)______Maple_______________Ridge________d=(a)______Summit
|<----d=(4b)----->|
First statement: Ridge is 3 times farther from Harbor as it is from Summit.
Let distance between Ridge and Summit be 'a'
Therefore dist. b/w Ridge and Harbor is 3a
Second statement: Maple is 4 times farther from Ridge as it is from Harbor,
Let distance between Harbor and Maple be 'b'
Therefor dist. b/w Maple and Ridge is 4b
Now we can see that 3a=4b+b
Thus, 3a=5b
Thus, 3a/5=b
We need to find dist (Maple,Summit) / dist (Harbor, Summit)
We know from the above diagram, that Dist(Maple,Summit) = Dist(Maple,Ridge)+Dist(Ridge,Summit)=4b+a
We also know, b=3a/5
Thus, 4b=12a/5
Thus 4b+a=(12a/5)+a=17a/5
Also, Dist (Harbor,Summit)=a+3a=4a
Thus the ratio then becomes, (17a/5)/4a=17/20
Answer is D