At the begining the pant was 2cm
One week after, it is 2.5cm
Pant size = 2 + 0.5 week
s = 2 + 0.5w
Where s is the plant size and w is the number of weeks
If the plant is 18 cm, using the formula we found, we can write:
s = 2 + 0.5 w
18 = 2 + 0.5w
18 - 2 = 0.5w
16 = 0.5w
w = 16/0.5 = 32
w = 32
Answers:
1. s = 2 + 0.5w (Where s is the plant size and w is the number of weeks)
2. 32 weeks