Answer:
9 rolls
Step-by-step explanation:
The perimeter of the room measures 2(19' +12') = 62', so the area of the walls is ...
(62 ft)(8.5 ft) = 527 ft²
We know that 8 rolls will cover 8×60 ft² = 480 ft², and 9 rolls will cover 540 ft², so we will need 9 rolls to cover the walls.