If a + b - c = 2d, and if a - b + c = 2e, then a =  Choose the most appropriate option.
A) 2(d + e)
B) d + e
C) (d + e)/2
D) d-2e
E) e-d
Add both equations:   a + b - c = 2d   a - b + c = 2e   a+b-c+a-b+c=2d+2e   2a=2d+2e   a=(d+e)   Ans:d + e
<result>B</result>
If a + b - c = 2d, and if a - b + c = 2e, then a =