<PRE><B>Question 703349</B>
A+C = 180


B + D = 180


C + D = 90


-------------------------------------------------------


Add the first two equations


A + B + C + D = 180 + 180


A + B + (C + D) = 360


A + B + 90 = 360


A + B = 360 - 90


A + B = 270


So the answer is choice C
</PRE>