<PRE><B>Question 192689</B>
1st: x
2nd: x + d
3rd: x = 2d
x + x + d + x + 2d = 21
3x+3d = 21
x + d = 7
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x(x+d)(x+2d) = 180
x(7)(x+2d) = 180
7x^2 + 14xd - 180 = 0
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Solve the system using substitution: d = 7-x
7x^2 + 14x(7-x) - 180 = 0
7x^2 + 98x - 14x^2 - 180 = 0
-7x^2 + 98x - 180 = 0
x = 11.83 or x = 2.174..
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Find d using d = 7-x
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Cheers,
Stan H.

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