Final answer:
After calculating that Tanya needs 180 candies (15 godchildren × 12 candies per godchild), and she already has 150, she would need to buy 30 more candies. However, this does not match any of the options provided.
Step-by-step explanation:
If Tanya plans to give a dozen candies to each one of her 15 godchildren, and she currently has 150 pieces of candy, we need to calculate the total number of candies she needs and compare it with what she already has. We start by multiplying the number of godchildren (15) by the number of candies per godchild (a dozen, which is 12), to determine the total amount needed.
Total candies needed = Number of godchildren × Candies per godchild
Total candies needed = 15 × 12
Total candies needed = 180
Since Tanya has 150 candies already, we subtract this number from the total number needed to find out how many more she needs to buy.
Candies to buy = Total needed - Candies on hand
Candies to buy = 180 - 150
Candies to buy = 30
However, there are no options that match this result in the question, which might indicate a typo or calculation mistake in the options provided. If the options mentioned are correct and 30 isn't an option, then the choices do not reflect the correct answer based on the data given.