if ( a - b - c + d = 18 ) and ( a + b - c - d = 4 ), what is the value of ( b - d ) ^ 2? Choose the correct choice from the following choices:
A) 49 .
B) 8 .
C) 12 .
D) 16 .
E) 64 .
<gadget id="calculator">18 + 4</gadget>
<output>22</output>

<gadget id="calculator">22 / 2</gadget>
<output>11</output>

<gadget id="calculator">4 - 11</gadget>
<output>-7</output>

<gadget id="calculator">(-7) ** 2</gadget>
<output>49</output>

<result>A</result>
if ( a - b - c + d = 18 ) and ( a + b - c - d = 4 ), what is the value of ( b - d ) ^ 2?
power(subtract(4, divide(add(18, 4), 2)), 2)
"eq 1 : a - b - c + d = 18 eq 2 : a + b - c - d = 4 ( 1 ) subtract eq 1 from eq 2 a - b - c + d = 18 - a + b - c - d = 4 - - - - - - - - - - - - - - - - - - - - - - - - - 2 b + 2 d = 14 ( 2 ) simplify - b + d = 7 b - d = - 7 ( b - d ) ^ 2 = ( - 7 ) ^ 2 = 49 my answer : a"