Final answer:
To find the proportion of cats and dogs in the total, we need to divide the sum of their numbers by the total number of animals. Given the ratio 18:20:7, the proportion is 60%.
Step-by-step explanation:
To find the proportion of the total that cats and dogs make up, we need to divide the sum of the number of cats and dogs by the total number of animals. Given that the ratio of rabbits, cats, and dogs is 18:20:7, we can represent this as 18x:20x:7x, where x is the common ratio. The sum of the parts is 18x + 20x + 7x = 45x.
The proportion of cats and dogs is (20x + 7x) / 45x. To find this proportion in percentage form, we can simplify the expression by canceling out the common factor of x: 27x / 45x = 3/5 = 0.6. Multiply by 100% to convert to a percentage: 0.6 x 100% = 60%