Question 1128326
<br>
Given:
(1) a+b = c
(2) a+c = d
(3) b = c+d
(4) d is a positive integer<br>
Substituting (3) into (1),<br>
a+c+d = c
a+d = 0
a = -d<br>
Since d is a positive integer, a is a negative integer.  The greatest value for a is when d has its minimum value of 1; then a is -1.<br>
ANSWER: E) -1