Answer:
7.65
Step-by-step explanation:
The total cost for 8 is 20.40, so you want to find what the cost for one panel is by dividing the total cost by the amount, which would be 20.40/8=2.55 then you want to know how much 3 of them cost, to find that you just multiply the cost of one of them by three, which would be 7.65
