To determine which answer is correct, apply the given ratio. 1/20:? Just by looking at it we know C is wrong. 4:100 is simplified to 1:25. B is also wrong, as 180:9 is 20:1, which is backwards from 1:20. However, A is correct because 9:180 is 1:20. D is also wrong for the same reasons B and C are wrong. Your answer is A!
