1. Make 21 with 3 coins.

 

 

 

 

 

 

 

2. Make 21 with 4 coins.

 

 

 

 

 

 

 

3. Make 21 with 5 coins.

 

 

 

 

 

 

 

4. Make 51 with 3 coins.

 

 

 

 

 

 

 

5. Make 51 with 6 coins.

 

 

 

 

 

 

6. Make 51 with 5 coins.