The trick here is to try and visualise the question. Ratios will stay the same as long as we multiply both sides. (Imagine a Regular sized pizza vs a Medium sized pizza and multiplying the ratio = increasing the amount of slice per pizza. The overall ratio of the size of the two pizza is still the same)

Knowing that, we try to find a common ground, in this question, how can we make it so that we can divide the Long ribbon into 3 parts to make the ratio of 1:2?