Answer: 63 cupcakes
Explanation:
1. Find the amount it took to bake 3 cakes:
3*30=90 minutes
2. Subtract 90 minutes from total minutes(12 hours):
720 mins-90 mins=630 mins
3. Find how many cupcakes you can make in 630 mins:
630/10=63
Solved
Have a nice day :D