We know they send parcels in equal amounts.

We need to calculate how many stamps are needed for each parcel:

The 24c parcel is sent using 4 of the 6c stamps.

The 30c parcel is sent using 1 of the 30c stamps.

The 72c parcel is sent using 2 of the 30c stamps and 2 of the 6c stamps.

In total this comes up to 6 of the 6c stamps and 3 of the 30c stamps needed.

The simplest ratio between 6:3 is 3:1

1 Like

Oh, thats right ,thanks alot