Problem Solving Strategy: Working Backwards.?

Question

A snail is crawling along a meter stick. At a certain point the snail stops. The snail needs to crawl 3 times as far as it has already crawled in order to be 4 cm from the end. How far has the snail already crawled?

Answer 1

Algebra is not necessary here. If it needs to crawl 3 times as far to be 4cm from the end, then it is easy to see that there are 4 equal distances, 1 that it has crawled already and 3 times that same distance. So 100 - 4 = 96. 96/4 = 24 cm

Answer 2

This should be in math section, but whatever.

Here's the start of it:

Let x be the distance the snail has crawled.

100 cm = x + 3x + 4 cm

Solve.