Divide the first number by the first number in the ratio, then the second number and see which ones are the same:
1.
24/3 = 8, 54/9 = 6
18/3 = 6, 54/9 = 6
36/3 = 12, 81/9 = 9
The answer is 18:54
2. 18/30 = 0.6
The ratio needs to be equal to 0.6
2/3 = 0.66
3/5 = 0.6
4/5 = 0.8
The answer is 3:5
3. Divide Y by X:
24/18 = 1.33
The Y value is the X value multiplied by 1.33
Y = 48 x 1.333 = 64
The answer is 64