A firm makes $x$ units of product M and $y$ of product N. Machine time is 3 h for M and 1 h for N, with 15 h available; labour is 1 h for M and 2 h for N, with 10 h available. Which constraints are right?

Explanation

1. 01

   Write each resource as (amount used per unit) × (number of units), added over the products.

2. 02

   'At most' or 'available' gives ≤, 'at least' or 'must give' gives ≥; a profit is maximised and a cost minimised.