AB + CD = AAA, where AB and CD are two-digit numbers and AAA is a three digit number; A, B, C, and D are distinct positive integers. In the addition problem above, what is the value of C?  Choose the correct answer
A) 1	B) 3	C) 7	D) 9	E) Cannot be determined
AB and CD are two digit integers, their sum can give us only one three digit integer of a kind of AAA it's 111.   So, A=1. 1B+C9=111   Now, C can not be less than 9, because no to digit integer with first digit 1 (mean that it's&lt;20) can be added to two digit integer less than 90 to have the sum 111 (if C9&lt;90 meaning C&lt;9 C9+1B&lt;111) --&gt; C=9   Answer: 9.
<result>D</result>
AB + CD = AAA, where AB and CD are two-digit numbers and AAA is a three digit number; A, B, C, and D are distinct positive integers. In the addition problem above, what is the value of C?