The ratio is 12:27
Since there is a total of 162 students, you can divide 162 by 27 to see how/by how much larger 162 is to 27.
162/27 = 6
162 is larger than 27 by 6 times. To maintain the ratio, you can multiply 12 by 6. 6(12:27)
12 · 6 = 72
72 students would have a dog