1. I received five heart-shaped letters in the morning and 1 in the afternoon. How many letters did I receive today?

5+ 1=6

2. I received 9 heart-shaped letters today and sent 3. How many letters are left?

9 - 3=6

I received three diamond letters in the morning and four in the afternoon. How many letters did I receive today?

3+4=7

I received eight diamond letters today, and four were sent. How many letters are left?

8-4=4

I received six triangular letters in the morning and four in the afternoon. How many letters did I receive today?

6+4= 10

6. I received 10 triangle letter today, and sent 2 letters. How many letters are left?

10-2=8