String A is 18 inches long.

String A is 15 inches shorter than string B. String C is half the length of string A. What is the total lenght of string B and string C?

String A is 18 inches long but 15 shorter than B. this means to get be you need to add string A (18) to 15. that would be 33 inches. string C is half the length of A (18) so you divide 18 by 2 (half) to get string C. that would 9 inches

String B: 33 inches

String C: 9 inches