Ask how many bugs each bird eats every day: 229.5/6=38.25.

Second, ask the four birds how many bugs they eat every day: 9 18/6= 153.

Ask how many bugs each bird eats every day: 153/4=38.25.

The third type: solve by equation.

Suppose every bird eats X worms every day: 4*x*6=9 18.

The solution is x=38.25.