On a single-zero table if I bet on Low, Even and Red I can cover all numbers on the board except 0, 29, 31, 33 and 35

What bets should I place on each of those 3 even chance sections so that I always end up with 1 unit profit should the ball land on any of those 32 numbers - or if that's not possible then what is the optimal bet that results in the greatest chance of profit vs. loss?

For example, if I bet (Low = 3), (Even = 1), (Red = 1) I win 3-5 units of profit if it lands on 14,16,18, but lose 3 units of profit if I land on 19-28. I also get 3 units of profit on most of the low numbers and 1 unit of profit on most of the mid-section numbers. I lose 1 unit on 11,30,32,34,36. How can I modify those 3 bets so that I always get a profit??

Any help would be much appreciated!

I tried to figure out 3 simultaneous equations/inequalities if one chip is 10, but there's not enough information to come up with the optimal answers plus my Maths is very rusty:

10 * 2 - x - y > 0

x * 2 - 10 - y > 0

y * 2 - 10 - x > 0

Any other ideas on covering the board using only outside bets?