Answer:
20 hours
Explanation:
First, it would be easiest to find how long it will take to bake 1 cake. We can take 5/6 and multiply it by 100 to put it into a percentage form. Then we divide by 75 (3/4 is 75%). This gives us 1.11 hours to bake 1 cake. We then multiply 1.11 by 18 (for 18 cakes) and our final answer is 20 hours to bake 18 cakes.