I'll do the first question.
The problem says that the length is 4 times the width. Let x be the size of the width for one of the two sides, that means that the length is 4x. Keep in mind that you have two sides for the width and two for the length. From this point just add the two widths and the two lengths which equals 2,000 and solve for x which will give you your answer.
Similar reasoning applies to the other problems.