Your first sum is correct. Think 100 pairs of numbers with each pair adding up to 201 (1+200, 2+199, 3+198, etc)

The 2nd sum can be done in the same way. Add up all the numbers from 1 to 199. Subtract the series:

2+4+6+8+...198

Subtract the series

3+6+9+12+...198

Add back the series

6+12+18+...198.

I think this is called inclusion/exclusion.