4. The animal shelter rescued 40 cats and dogs today. If 12 of them were cats, what percent of them were dogs?

Should I solve by subtracting 40-12 to get the number of dogs or solve using the cats and then subtracting that from 100?

40-12 = 28 dogs
28/40 = x/100
40x = 2800
x = 2800/40
x = 70% dogs

Or
12/40 = x/100
40x = 1200
x = 1200/40
x = 30% cats

100%-30% = 70% dogs