Answer:
50+80t=c
Explanation:
First, we add 50 as a constant, because it is an initial cost.
Then, since they are charged 80$ every month, we can add 80t to the equation, with t representing the amount of months installed.
Lastly, we can add a equal sign and c, since the total cost is equal to the initial price plus the amount of months.
Hope this helps!