Answer:
6 spaniels
Explanation:
Create 2 equations to represent this, where b is the number of boxers and s is the number of spaniels:
4s = b
s + b = 30
We can plug in 4s as b into the second equation, s + b = 30:
s + b = 30
s + 4s = 30
5s = 30
s = 6
So, there are 6 spaniels.