Hang on a minute!

crop_width and crop_x are saved as strings, so...

crop_width = '1.0'
crop_x = '2.5'

(crop_width + crop_x).to_f # 1.02

I think you may want..

crop_width.to_f + crop_x.to_f # 3.5

(I haven't refactored that, but I would)

Unless I'm wrong (happy to be wrong: please tell me if so), the version in the episode may trip up a few people

Meant constructively, as ever!