This is level 12 of Plan A.
The best character to beat this level is the Duplicator. With his short jumps he can reach each platform easily from the beginning of the level. If you find a large gap between two platforms you can jump on your duplicates and get to that platform. At the end just jump on the crumbling bridge and jump to the end of the level.
If you haven't unlocked the Duplicator, then use the Child. Step on the crumbling bridge until the end, then long jump onto the left of the box. Then, instantly jump onto the second crumbling bridge to finish the level.