我们班一共有40人,其中乘公共汽车上学的有20人,乘小汽车上学的有10人,骑自行车的6人,步行的有4人.

There are altogether 40 students in our class.Twenty of the students go to school by bus,10 students by car,6 by bike and 4 on foot.
I think we can go to school by bike,because it is easy and safe.

There are 40 students in our class, 20 of which go to school by bus, 10 of which by car, 6 of which by bike and 4of which on foot.

Our class has 40 students in total.20 of them take the bus to school. 10 of them are by cars.6 students ride their bike and 4 people walk to school.
you can't really say which one is better.It depends on how far from your home to school. But, in my opinion,taking the bus or ride bike to school is good enough !!