To find the constant of proportionality \( k \) for the variation where \( y \) varies directly with \( x \), we can use the relationship given by the formula:
\[ y = kx \]
From the information given, we know:
- When \( x + 5 \), \( y + 35 \).
This can be interpreted as:
- When \( x = 5 \), \( y = 35 \).
We can substitute these values into the direct variation equation to find \( k \).
- Substitute \( x = 5 \) and \( y = 35 \) into the equation:
\[ 35 = k(5) \]
- Solve for \( k \):
\[ k = \frac{35}{5} = 7 \]
Thus, the value of the constant of proportionality \( k \) is:
\[ \boxed{7} \]
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