Data given for favourite pet
Horse = 4/10
cat = 2/10
Dog = 4/10
Bird = 0/10
The fraction of the club that chooses a horse as their favourite pet = 4/10
The fraction of the club that chooses a bird as their favourite pet = 0/10
The total fraction of the club that chooses a horse or bird as their favourite pet is given as
[tex]\frac{4}{10\text{ }}+\frac{0}{10}=\frac{4}{10}[/tex]