Question

the ratio of cats to dogs seen by a veterinarian in one day is 2 to 5. If a vet saw 40 dogs in one day,how many cats did he see?

Answer 1

2 cats to every 5 dogs
x cats to every 40 dogs

x/40 = 2/5    
(here you can cross multiply OR multiply the second fraction by 8/8)

x = 16        the vet saw 16 cats