Final answer:
To find the markup rate, subtract the purchase price from the selling price and divide the result by the purchase price. In this case, the markup rate is 60%.
Step-by-step explanation:
To find the markup rate, we need to subtract the purchase price from the selling price and then divide the result by the purchase price. In this case, the purchase price is $90 and the selling price is $144. So the markup would be $144 - $90 = $54. Now, divide this markup amount by the purchase price: $54 / $90 = 0.6. Finally, multiply this result by 100 to convert it to a percentage: 0.6 * 100 = 60%. Therefore, the markup rate is 60%.