The numbers inside the rectangles represent the area of these rectangles. What is the area of the green rectangle?
+23246 Let a be the length across the top of the red rectangle.
Let b be the length across the top of the blue rectangle.
Let c be the height across the left side of the red rectangle.
Let d be the height across the left side of the yellow rectangle.
Therefore, the area of the
red rectangle is: a·c = 12
blue rectangle is: b·c = 15
yellow rectangle is: a·d = 8
green rectangle is: b·d = ??
a·c = 12 ---> a = 12/c
a·d = 8 ---> a = 8/d
Combining these two equations: 12/c = 8/d ---> 12d = 8c ---> 3d = 2c ---> c = 3d/2
b·c = 15 ---> c = 15/b
Combining c = 15/b with c = 3d/2 ---> 15/b = 3d/2 ---> 3bd = 30 ---> b·d = 10
