You may have correctly found the separate probabilities of rolling doubles and getting heads, and then added these two fractions. Instead, use the Fundamental Counting Principle to find the size of the sample space. Each die has six possible outcomes and the coin has two. Then write out the event space, which includes outcomes such as (1, 1, H), and find its size by counting. Finally, divide the size of the event space by the size of the sample space.