求教一道problem solving（GWD29）

norlanzhang

A rectangular photograph is surrounded by a border that is 1 inch wide on each side.The total area of the photograph and the border is M square inches. If the border had been 2 inches wide on each side, the total area would have been M+52 square inches. What is the perimeter of the photograph, in inches?
A. 34
B. 36
C.38
D.40
E.42

sdcar2010

Old: length x, width y
New: length x+4, width y+4
(x+2)*(y+2)=M
(x+4)*(y+4)=M+52
So, x+y = 20

Perimeter = 2*(x+y) = 40

DDDDDDDDDDDDDddd

norlanzhang

er...thx。弱弱地问一下，题中那个1inch和2inch怎么理解？

kazemi

想想一个大长方形里面套一个小长方形，大长方形和小长方形对应的边之间的距离