GRE
The product when multiplying 9 and the number of times he picks up 2 point cards
The number of times he picks up 4 point cards
$$(x+y+z)^{2}$$
1
2x
y
$$\frac{a}{c}$$
$$\frac{(a+k)}{(c+k)}$$
($$\frac{2}{3}$$@$$\frac{2}{3}$$)@$$\frac{2}{3}$$
$$\frac{2}{3}$$@($$\frac{2}{3}$$@$$\frac{2}{3}$$)
(x+1)@
$$x^{2}$$
c@3, where c > 3
3
4@(2@9)
(4@2)@9
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