Final answer:
The system of inequalities that represents the situation of buying at least 6 ringtones without spending more than $15, with premium ringtones costing $1.50 and top-10 ringtones costing $3, is a) 1.5x + 3y ≤ 15, x + y ≥ 6.
Step-by-step explanation:
The situation described in the student's question involves purchasing at least 6 new ringtones without spending more than $15. Premium ringtones, designated as x, cost $1.50 each, while top-10 ringtones, designated as y, cost $3 each. To represent this scenario, we need to establish two inequalities.
The first inequality will ensure that the total cost does not exceed $15, which can be written as 1.5x + 3y ≤ 15. The second inequality will ensure that the student buys at least 6 ringtones, which translates to x + y ≥ 6.
Combining both inequalities gives us the system that represents the situation: a) 1.5x + 3y ≤ 15, x + y ≥ 6.