Step 1: Convert the decimal value 345 to a base-3 or unbalanced ternary value:

3 / 345 \ 115   Remainder = 0       <- least significant
    3
    -
    04
     3
     -
     15
     15
     --
      0

3 / 115 \ 38    Remainder = 1
     9
     -
     25
     24
     --
      1
      
3 / 38 \ 12     Remainder = 2
    3
    -
    08
     6
     -
     2    
     
3 / 12 \ 4      Remainder = 0
    12
    --
     0   
     
3 / 4 \ 1       Remainder = 1
    3
    -
    1    
    
3 / 1 \ 0       Remainder = 1       <- most significant
    0
    -
    1       
    
Answer:  The base-10 value 345 converted to a base-3 value is: 110210