4inches and 4yards that is what I got but it might be wrong
There are 25 students in the class
C+d=14
c-6=d
then you will plug c+6 in the first equation and you will get:
c+c-6=14
then you get
2c=20
c=10, so the cat is ten years old
the cat is 6 years older than the dog, so the dog is 4 years old
hope that helps :)
Its called the zero property of addition