29. New grass seeds grow rapidly. A grass seed has grown to 0.3 millimeters tall. Tomorrow it will be 0.9 millimeters
tall, the next day it will be 1.5 millimeters tall, and on the next day it will be 2.1 millimeters tall. Write a rule to
represent the height of the bean plant as an arithmetic sequence. How tall will the plant be in 15?