Hi there!
To solve this problem, let's set up a proportion: 1/30 = x/45. Now, cross-multiply to get an equation: 30x = 45. Now, divide each side by 30 to figure out how many centimeters would be used to represent 45 kilometers: x = 2/3 or 0.666 cm.
Hope this helps!! :)
If there's anything else that I can help you with, please let me know!