Answer:
1 U.S. dollar equals 6.4185 Chinese yuans. The correct answer is D.
Explanation:
- The first step is to get a fraction between the currencies. The fraction is obtained by dividing the 1 yuan by 0.1558 U.S. dollars.

- The second step is to multiply the previous fraction by 1 U.S. dollar.

As you can see, the U.S. dollar units can be cancelled and yuan remains.

- The last step is to perform the division.

Thus, 1 U.S. dollar equals 6.4185 Chinese yuans. The correct answer is D.