ab + cd = jjj , where ab and cd are two - digit numbers and jjj is a 3 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 choice from the following answers
A) 1	B) 3	C) 7	D) 9	E) can not be determined

Rationale: ab and cd are two digit integers , their sum can give us only one three digit integer of a kind of jjj it ' s 111 . so , a = 1 . 1 b + cd = 111 now , c can not be less than 9 , because no to digit integer with first digit 1 ( mean that it ' s < 20 ) can be added to two digit integer less than 90 to have the sum 111 ( if cd < 90 meaning c < 9 cd + 1 b < 111 ) - - > c = 9 answer : d .
Answer: D