To evaluate how many cookies Mark can bake with 6 scoops of flour, we can substitute \( f = 6 \) into the equation \( c = 7f \).
Given:
\[ c = 7f \]
Now, substitute \( f \) with 6:
\[ c = 7 \times 6 \]
Calculating that gives:
\[ c = 42 \]
So, with 6 scoops of flour, Mark can bake 42 cookies.