Let \( s \) represent the number of seashells Ian used to decorate each frame. Since he used the same number of seashells for each of the 7 frames and a total of 63 seashells, we can model the situation with the following equation:
\[ 7s = 63 \]
To find out how many seashells Ian used to decorate each frame, we will solve the equation for \( s \):
- Divide both sides of the equation by 7:
\[ s = \frac{63}{7} \]
- Calculate the right side:
\[ s = 9 \]
So, Ian used 9 seashells to decorate each frame.