To determine how many tablespoons of vinegar Ellen needs for 16 color tablets, we first analyze the ratio provided: Ellen uses 5 tablespoons of vinegar for every 2 color tablets.
To find out how many groups of 2 color tablets are in 16 color tablets, we divide 16 by 2:
\[ 16 \div 2 = 8 \]
This means there are 8 groups of 2 color tablets in 16 tablets. Since each group requires 5 tablespoons of vinegar, we calculate the total amount of vinegar needed by multiplying the number of groups by the tablespoons of vinegar needed per group:
\[ 8 \times 5 = 40 \]
Thus, Ellen will need 40 tablespoons of vinegar for 16 color tablets.