Final answer:
A system of equations to model the situation is 4l + 8m = $40 for the first scenario, and 5l + 2m = $28 for the second scenario, where l represents the cost of a large plant and m represents the cost of a medium plant.
Step-by-step explanation:
To model the situation where the cost of 4 large plants and 8 medium plants is $40, and the cost of 5 large plants and 2 medium plants is $28, we can set up a system of equations using two variables, l for the cost of a large plant and m for the cost of a medium plant.
The two equations based on the given information would be:
1. For 4 large plants and 8 medium plants: 4l + 8m = $40
2. For 5 large plants and 2 medium plants: 5l + 2m = $28
Now, you can solve this system of equations using methods such as substitution or elimination to find the individual prices of the large and the medium plants.