DS - Machines X and Y work

Hi there,

Could you explain the concept of this DS in simplest way

Machines X and Y work at their respective constant rates. How many more hours does it take
machine Y, working along, to fill a production order of a certain size than it takes machine X,
working alone?

(1) Machines X and Y, working together, fill a production order of this size in two-thirds the time
that machine X, working alone, does.

(2) Machine Y, working alone, fills a production order of this size in twice that machine X,
working alone, does.