Answer: 63 cm tall.
Step-by-step explanation: Yolanda's sunflower is 12 cm more than Jean's sunflower. Yolanda's sunflower is 75cm. To find Jean's sunflower's size in cm simply subtract 12 cm from 75 cm.
75 = 12 = 63
So, Jean's sunflower is 63 centimeters tall.