You see a row of 5 trees, each one 20 meters from the next. How long is the row?

Question

I'm thinking of this problem in 2 ways.

1. There's 5 trees, each the same width $X$. This leaves 4 inner "gaps" of $20$ meters in length? So, my answer would be $(20 \times 4) + (5\times X)$ or rather $80 + 5x$

2. If there's 2 trees, from each end including the inner gap is $20$ meters. If there's 3 trees, then it from tree one to tree three would be $40$ meters. Going by this 4 trees would be $60$ meters, and 5 trees would be $80$ meters. Not sure what this would be in the form of an equation.

Thoughts on what is more valid? And any tips regarding how to interpret similar questions?

Answer 1

You get the same answer in both cases - 80 meters - except in one case you account for the width of the trees, and in the other you don't.

The question as stated isn't clear how it counts the width of the trees, and as stated it probably assumes it's negligible compared to the width of the gaps (a reasonable assumption in reality as well).