1) Worth: adjective or noun, means value
- How much is that watch worth?
- What is the boat worth?
2) Worthy: adjective, means having or showing qualities or abilities that merit recognition
- Do you think that option is worthy of consideration?
- We went to the charity event which donates the proceeds to a worthy cause.
3) Worthwhile: adjective, worth the time, money or effort
- I think visiting the museum would be worthwhile.
- Adding new floors to the house increased the resale value, which I feel was worthwhile.
Hope that helps!