216. One says to the other: "Give me 7 denarii, and I will be 5 times richer than you." And the other says: "Give me 5 denarii, and I will be 7 times richer than you": How much does each have?
216. The question boils down to solving the system:

$$
x+7=5(y-7) ; y+5=7(x-5)
$$

from which $x=7 \frac{2}{17} ; y=9 \frac{14}{17}$.