Final answer:
To find the greatest number of pieces of fruit Mei can put in each basket, we need to find the greatest common divisor (GCD) of the given quantities of oranges, peaches, and pears. In this case, the GCD is 3. Therefore, Mei can put 3 pieces of fruit in each basket.
Step-by-step explanation:
To find the greatest number of pieces of fruit Mei can put in each basket, we need to find the greatest common divisor (GCD) of the given quantities of oranges, peaches, and pears. The GCD is the largest number that divides evenly into all three quantities. In this case, the GCD of 15, 9, and 18 is 3. Therefore, Mei can put 3 pieces of fruit in each basket.