A 3-digit number 4a3 is added to another 3-digit number 984 to give a 4-digit number 13b7, which is divisible by 11. Then, (a + b) = ?  Pick one:  A) 10  B) 11  C) 23  D) 43  E) 66
10   10   4 a 3 |   9 8 4 } ==&gt; a + 8 = b ==&gt; b - a = 8   13 b 7 |   10lso, 13 b7 is divisible by 11 (7 + 3) - (b + 1) = (9 - b)   (9 - b) = 0   b = 9   (b = 9 and a = 1) (a + b) = 10.
<result>A</result>
A 3-digit number 4a3 is added to another 3-digit number 984 to give a 4-digit number 13b7, which is divisible by 11. Then, (a + b) = ?