From the question, last Monday, a local mail carriers delivered 1,344 pieces of mail and of all the deliveries they made, 1 / 6 were magazines, 1 / 12 were packages, and the rest were letters. The fraction of letters will be:
= 1 - (1/6 + 1/12)
= 1 - (3/12)
= 9/12 = 3/4
We will now multiply 3/4 by 1344 to get the number of letters delivered.