Please help me with my assignment it's a Collins type 3 (question is in the picture)

Something a student can do wrong is, maybe adding or doing the wrong arithmetic in the problem. You may want to avoid because it can mess up the whole equation and that leads to getting the wrong answer, so it is always good to check what you are doing be for you finish your answer.

what is the question? i am guessing you are looking for the area.

to find an area, you have to do length x width.

in this case, it would be 12 ft x 4 ft = 48 sq. ft