Answer:
Step-by-step explanation:
Variables are defined in the problem statement.
 18x +15y ≤ 300 . . . . total budget
 y ≥ 6 . . . . . . . . . . . .  minimum number of annuals
 x ≥ 0 . . . . . number of perennials cannot be negative
This system of inequalities describes the situation.