Each of the positive integers a and c is a four-digit integer. If each of the digits 0 through 9 appears in one of these three integers, what is the maximum possible value of the sum of a and c? Options:	A) 18695	B) 18325	C) 18365	D) 18395	E) 18485
According to the stem we should use the digits 0 through 9 to construct 2 four-digit integers, so that their sum is as big as possible.   To maximize the sum, maximize the thousands digits of a and c, so make them 9 and 8.   Next, maximize hundreds digits. Make them 7 and 6 .   Next maximize 10's digit place by 5 and 4   Use the remaining digits (3,and 2) for units digits.   So, a would be 9753,and c would be 8642.   9753 + 8642= 
<gadget id="calculator">9753 + 8642</gadget>
<output>18_395</output>
18395   Answer: 18395.
<result>D</result>
Each of the positive integers a and c is a four-digit integer. If each of the digits 0 through 9 appears in one of these three integers, what is the maximum possible value of the sum of a and c?