To expand the expression \( \frac{7}{10}(5d + 6) \), you distribute \( \frac{7}{10} \) to both terms inside the parentheses:
\[ \frac{7}{10} \cdot 5d + \frac{7}{10} \cdot 6 \]
Calculating each term:
- \( \frac{7}{10} \cdot 5d = \frac{35}{10}d = 3.5d \) or \( 35d/10 \)
- \( \frac{7}{10} \cdot 6 = \frac{42}{10} = 4.2 \)
So, the expanded expression is:
\[ 3.5d + 4.2 \]
None of the given responses match this directly, but looking through them, we can see:
- \( 35d + 42 \)
- \( 35d + 4.2 \) could be represented as \( \frac{42}{10} \) in an equivalent fraction form depending on context.
If we simplify the correct overall answer to the options given, considering mistakes might have occurred in typing out the responses, the likely option that best resembles our correct work is:
35d + 42
However, if \( \frac{7}{10}(5d + 6) \) should yield something near:
- 3.5d + 4.2
In conclusion, the expansion is \( 3.5d + 4.2 \), and out of the given options, 35d + 4.2 might be the assumed correct interpretation fitting our obtained results.