This question has two parts - I've solved the first part, only I can't seem to find a way to solve the second part:

*Let A,B,C be sets. Prove that if B,C ⊆ A , |C|=|B|, andB∩C=then |A-B|=|A-C|.

now, I understand that somehow I probably need to use a few sets I know:

*Find, using the first part, the cardinal number of all the real irrational numbers between 0 and 1.

Q - the rational numbers, |Q|=Alef 0 (|Q|=|N|)

(0,1) - as required. If I'm not mistaking, it's cardinal number is also Alef 0.

Please help me figure this out. Thank you !