4. In my school, $60 \%$ of the teachers come to school by bicycle. There are 45 teachers who come to school by bicycle. Only $12 \%$ come to school by car. How many teachers come to school by car?
A 4
B 6
C 9
D 10
E 12
4. C The percentage of teachers coming to school by car is one fifth of the percentage of teachers coming to school by bicycle. Therefore, the number of teachers coming to school by car is $\frac{1}{5} \times 45=9$.