Matthias has 40 soccer balls and 15 basketballs. 30 soccer balls and 7 basketballs have a hole in them. How many balls in total does Matthias have without holes in them? Let's think first. Chain of thought:
Matthias has 40 - 30 = 10 soccer balls without holes. Matthias has 15 - 7 = 8 basketballs without holes. A total of 10 + 8 = 18 balls do not have holes.
Therefore, the answer is 18.