Answer:
Cost of a fern = $4
cost of a rose bush = $3
Step-by-step explanation:
Let cost of a fern in dollars be = 
Let cost of a rosebush in dollars be = 
Matt purchased 8 ferns and 1 rosebush for $35
Cost of 8 ferns in dollars will be = 
cost of a rosebush in dollars is = 
Total cost of 8 ferns and 1 rosebush in dollars = 
So, we have a Matt's equation as:

Trey purchased 4 ferns and 3 rosebushes for $25.
Cost of 4 ferns in dollars = 
Cost of 3 rosebushes in dollars = 
Total cost of 4 ferns and 3 rosebush in dollars = 
So, we have a Trey's equation as:

The system of equations is :
A) 
B) 
Solving the system by substitution method.
Rearranging equation A, to solve for
in terms of 
Subtracting both sides by 


Substituting value of
we got from A into equation B.

Using distribution.

Simplifying.

Subtracting both sides by 105.


Dividing both sides by -20.

∴ 
We can plugin
in the rearranged equation A to get value of 


∴ 
Cost of a fern = $4
Cost of a rosebush = $3