Answer:
45 minutes
Step-by-step explanation:
30 minutes --> 12 miles
? minutes ----> 18 miles
18÷12 = 1.5
30 × 1.5 = 45
45 minutes --> 18 miles
It's steepness decreases
If you graph both, you can see it's less steep. Sorry I don't know if there's any other faster way.
8
72.8