Answer:
520
Explanation:
Let's say the x = smallest number of units that must be assembled during the regular hours, and 660-x is the number of units that can be assembled in overtime. Then, the total cost should be smaller than or equal to cost1 *x + cost2*3.75
⇒ (x * 2.65) + ((660 - x) * 3.75) <= 1903
⇒ x * (2.65 - 3.75) + (660 * 3.75) <= 1903
⇒ 1.1 * x >= 2475 - 1903
⇒ 1.1 * x >= 572
⇒ x >= 520