Answer :

42 times 10 
210 times 2
210 + 210
70 times 6
60 tmes 7
140 times 3

 
and etc
If we do it algebraically, we get

x + y = 420

This is the simplest equation. You see now this is a linear pair in two variables. Thus, there will be infinitely many solutions.

E.g - 419 + 1 = 420

42 * 10 = 420
21 * 20 = 420

etc,....