16. (12 points) The school is holding a math oral quick-answer competition, with a total of 100 questions. The competition rules are: 10 points for a correct answer, and a deduction of 5 points for a wrong answer. The final result of the competition is that Class 4 (2) scored a total of 850 points. How many questions did Class 4 (2) answer incorrectly?
【Solution】Solve: $(10 \times 100-7850) \div(10+5)$
$$
\begin{array}{l}
=(1000-850) \div 15 \\
=150 \div 15 \\
=10 \text { (questions) }
\end{array}
$$

Answer: Class 4(2) answered 10 questions incorrectly.