David's total income is ($8/hr)x + ($11/hr)y.
This problem requires us to write and solve an inequality:
8x + 11(15)<$200
Solving for x: 8x < $200-$165, or 8x < $35. Strictly speaking, x = 4.375 hrs, but if we assume that David must work an integer # of hours, then x=5 full hours.