Not sure what the previous answers were, but here is one way:

x=8-xy ; y=9-xymultiply these togetherxy=(8-xy)(9-xy)xy=72 - 17xy + (xy)^2(xy)^2 -18xy + 72 = 0xy = (18 +/- sqrt(324-288))/2xy = 9 +/- 3 xy = {6, 12}

blackjack

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