1. The problem is to convert the mixed number $3 \frac{5}{10}$ into a decimal. 2. A mixed number consists of a whole number and a fraction. To convert it to a decimal, convert the fraction to a decimal and add it to the whole number. 3. The fraction is $\frac{5}{10}$. Dividing 5 by 10 gives $0.5$. 4. Add the decimal fraction to the whole number: $3 + 0.5 = 3.5$. 5. Therefore, the decimal equivalent of $3 \frac{5}{10}$ is $3.5$.