Question

juan bought 12 oranges and ate 1/4 of them
carla bought 12 oranges and ate 1/3 of them . which ate more

Answer 1

1/4 * 12 = ?

1/3 * 12 = ?

Answer 2

Or to put it another way,

1/1=1
1/2 is smaller
1/3 is smaller still
1/4 is even smaller.
this is because the number of pieces the whole (1) is divided into is getting larger as we go, so one of them gets smaller as the denominator gets bigger.