To determine the cost of 12 markers, we start by calculating the price of one marker. Ahmed bought 5 markers for $3.25, so the cost of one marker is:
\[ \text{Cost of one marker} = \frac{3.25}{5} = 0.65 \]
Now we can find the cost of 12 markers:
\[ \text{Cost of 12 markers} = 12 \times 0.65 = 7.80 \]
Thus, the cost for 12 markers is $7.80.