Neco 2020 Commerce Question 8

A small business uses two telephone services.\n\n- Mobile plan: monthly subscription \(\text{₦}5,000\) includes \(200\) minutes; each additional minute costs \(\text{₦}30\).\n- VOIP plan: monthly subscription \(\text{₦}2,500\) includes \(500\) minutes; each additional minute costs \(\text{₦}10\).\n\nEach month the business makes \(800\) minutes of calls, of which \(30\%\) are international and are charged at double the per‑minute rate of the plan on which they are billed. Minutes can be allocated between the two plans in any proportion.\n\nFind the allocation of minutes to the mobile and VOIP plans that minimises the total monthly cost and state that minimum cost.