Answer: she sells each egg for $0.52
Explanation:
The number of eggs that make a dozen is 12.
Miss Henry buys a dozen pens for $2.50. This means that the cost of each egg would be
2.5/12
If she marks up the price of each pen by 150% and sells them, the value of 150% mark up on the price of each egg is
2.5/12 × 150/100 = 2.5/12 × 1.5 = 0.3125
The price at which she sells each egg is
3.75/12 + 2.5/12 = 6.25/12 = $0.52