Step-by-step explanation:
From the original question, we can rewrite this as:
An airplane company is determining the difference in selling price if rows of first-class seats are added to a new design. The total selling price for one new row is f(r) = 4,000r. Each row in first class eliminates a pair of rows of economy seats. The total price for each pair of removed rows is e(r) = 1,800r. Which is d(r), the profit or loss for adding r rows of first class seats?
f(r) = 4000r
e(r) = 1800r
d(r) = ? (profit or loss)
Assuming we had added a row of first class seats,
+ f(r) = 4000r
But we had to remove a pair or rows from the economy seats,
- e(r) = 1800r
Translating these into one equation:
d(r) = f(r) - e(r) = 4000r - 1800r = 2200r
Therefore, OPTION A.) d(r) = 2200r
