问题详情

The length of a rectangle is 3 times the length of a smaller rectangle. The 2 rectangles have the same width. The area of the smaller rectangle is A square units. The area of the larger rectangle is kA square units.Which of the following is the value of k ？
A.1/9
B.1/3
C.1
D.3
E.9请帮忙给出正确答案和分析，谢谢！