$$^nP_r$$ = $$^nC_r$$*r!
$$^nP_x = 336$$
$$^nC_x *x!$$ = 336
x!= $$\ \frac{336}{56}$$
x!=6
x=3
$$^nC_x = 56$$
$$\ \ \frac{\ n!}{\left(n-x\right)!\times\ x!}\ =\ 56$$
$$\ \ \frac{\ n!}{\left(n-3\right)!\times\ 3!}\ =\ 56$$
n=8
$$\therefore$$ n= 8, x=3
C is the correct answer.
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