Hello, studman09!

There are square tiles arranged in a pattern.

The pattern has rows that are 5 tiles wide and an unknown number of rows.

If you add one more tile, you can create a pattern that has rows that are 3 tiles wide,

with 3 more rows than the original pattern.

How many rows are in the original pattern?

The original pattern had rows and 5 columns.

. . There were tiles.

Add one tile.

The tiles can be arranged in rows and 3 columns.

. . There will be: . tiles.

Thereis our equation: .