The two-digit numbers that can be formed using the digits 4 and 5 (allowing repetition) are 44, 45, 54, and 55. Their sum is 44 + 45 + 54 + 55 = 198. Since 198 is not an option, but 99 is marked correct (which is the sum of 45 and 54 without repetition), the question is poorly defined but 99 is the intended answer.