Answer:
12
Step-by-step explanation:
You have to add the amount Sidney paid with the money she got off. You get 48 then you have to divide 48 by the 4 months she paid for to get 12.
Cost without coupon=40+ 8=$48
Total months=4
Cost of each month:-
[tex]\\ \sf{:}\dashrightarrow 48/4[/tex]
[tex]\\ \sf{:}\dashrightarrow 12\$[/tex]