Question

Pupils at a scholl either arrive by bus,car or on foot. 3/10 walk and 1/3 come by bus. What fraction come by car?

Answer 1

the total of the pupils are the 100%, or in fraction mode, 1, the whole, so we have:
bus + car + foot = total
1/3 + car + 3/10 = 1
car = 1 - 3/10 - 1/3
car = 1 - (9/30 + 10/30)
car = 30/30 - 19/30
car = 11/30
that is the fraction that come by car