Article 1: 8. Article 2: (8+6) and Article 3: (8+6+6)

From the above, we can get:

The matching number used from the second fish to the nth fish is obtained by adding 6 to the matching number used by the last fish.

Then we can simplify the algebraic expression: 8+6(n- 1) to 2+6n.

Pure hands! ! !