Suppose you are determining the growth rate of two species of plants. species a is 12 cm tall and grows 2 cm per month. species b is 10 cm tall and grows 3 cm per month. which system of equations models the height of each species h(m) as a function of months m.

This is how to solve the problem:

We know that the growth rate is constant for both species of plants. So we can say that the height is a linear function of the number of days since d = 0. 

Assumption (1 month = 30 days)

Species A: 
Growth rate = 2 cm/month = 2/30 = 1/15 cm/day 
Height on day d = 0: 12 cm 
Height: H(d) = 12 + d/15 

Species B: 
Growth rate = 3 cm/month = 3/30 = 1/10 cm/day 
Height on day d = 0: 10 cm 
Height: H(d) = 10 + d/10