A cloud analytics firm offers a tiered monthly subscription based on API calls. Tier 1 covers up to 10,000 calls for a flat fee of $200. Tier 2 covers calls from 10,001 to 50,000, charging $0.015 per call for each call in that range. Tier 3 covers calls above 50,000, charging $0.008 per call for each call above 50,000. If a client's monthly call volume N exceeds 50,000, the client also receives a bulk rebate of $0.002 per call on all calls made in Tier 2. If a client's net monthly bill is $1,000