The equation given is:
\[
|-7x + 8| = 7
\]
The absolute value equation \( |A| = B \) implies that \( A = B \) or \( A = -B \). Therefore, we can split the equation into two cases:
\( -7x + 8 = 7 \)
\( -7x + 8 = -7 \)
Step 2: Solve the First Case
Solve \( -7x + 8 = 7 \):
\[
-7x + 8 = 7
\]
Subtract 8 from both sides:
\[
-7x = 7 - 8
\]
\[
-7x = -1
\]
Divide both sides by \(-7\):
\[
x = \frac{-1}{-7} = \frac{1}{7}
\]
Step 3: Solve the Second Case
Solve \( -7x + 8 = -7 \):
\[
-7x + 8 = -7
\]
Subtract 8 from both sides:
\[
-7x = -7 - 8
\]
\[
-7x = -15
\]
Divide both sides by \(-7\):
\[
x = \frac{-15}{-7} = \frac{15}{7}
\]
Final Answer
The solutions to the equation \( |-7x + 8| = 7 \) are:
\[
\boxed{\left\{\frac{1}{7}, \frac{15}{7}\right\}}
\]