Let the original price of the article be \( P \). The first discount of 10% reduces the price to \( 0.9P \). A subsequent 5% discount further reduces this price to \( 0.95 \times 0.9P = 0.855P \). Hence, the overall discount is:
\[
\text{Overall Discount} = P - 0.855P = 0.145P
\]
This corresponds to a 14.5% discount.
Thus, the correct answer is (c) 14.5%.