To find out how much Ms. Tanaka will earn for selling 12 televisions, we can plug \( t = 12 \) into the formula:
\[ \text{Earnings} = 2,500 + 100t \]
Substituting \( t = 12 \):
\[ \text{Earnings} = 2,500 + 100(12) \]
Calculating \( 100(12) \):
\[ 100(12) = 1,200 \]
Now, adding this to the base salary:
\[ \text{Earnings} = 2,500 + 1,200 = 3,700 \]
Therefore, Ms. Tanaka will earn $3,700 for selling 12 televisions this month.