Set 11: Linear Inequalities

Choice C is correct. Choice C is the correct answer. Net earnings per post should be factored before multiplying by number of posts. 1. Per-post earnings: $150- \45 = $105 net per post 2. Total for p$ posts: 105p or equivalently $(150-45)p$ 3. Constraint: Want at least \$420: $(150-45)p \geq 420$ Strategic Tip: When earnings and costs are per-unit, calculate net amount first, then multiply by quantity. Choice A is incorrect because it subtracts \45only once regardless of number of posts (should be $45 per post). Choice B is incorrect because it treats 45 as a coefficient of $$p, but the fee is \45 total per post, not $45 p. Choice D is incorrect because it has only one post earning $150, then subtracting a variable cost.