Explanation

Let us assume that the car was manufactured for $100.

Price it was sold to dealer (@20% higher)= \($100 + $100 \times \frac{20}{100}\) = $120.

Now dealer sells it @ 15% higher = \($120 + $120 \times \frac{15}{100}\) = $138.

We can see by putting d = 100. option E is correct.
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the car cost the consumer, in dollars = d *1.15 *1.2 = 1.38d

great explanation sandy. this question doesnt seem like it should be in the hard category

I would typically solve this questioning the same way Sandy did. However, here is an algebraic approach:

A car manufacturer produced a car at a cost of d dollars and sold it to a dealer at a price 20 percent higher than the production cost.
Dealer price = (cost price) + (20% of cost price)
Dealer price = d + (20% of d)
Dealer price = 1d + 0.2d
Dealer price = 1.2d

If the dealer sold the car to a consumer for 15 percent more than the dealer paid for it, what did the car cost the consumer, in dollars?
Consumer price = (dealer price) + (15% of dealer price)
Consumer price = (1.2d) + (15% of 1.2d)
Consumer price = (1.2d) + (0.15)(1.2d)
Consumer price = (1.2d) + (0.18d)
Consumer price = 1.38d

Answer: E
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