Answer:
Twelve.
Explanation:
This scenario can be interpreted by the ratio 3:8, with 3 being the amount of basil leaves and 8 being the amount of tomatoes. If there were 32 tomatoes in the sauce, then there would have been 12 basil leaves.
3:8
6:16
9:24
12:32
All of these ratios can simplify back down to 3:8.