The total weight of a tin and the cookies it contains is 2 pounds. After ¾ of the cookies are eaten, the tin and the remaining cookies weigh 0.8 pounds. What is the weight of the empty tin in pounds?
Correct Answer: 0.4
Let the weight of the empty tin = w
(2 - w) = weight of the cookies; and one quarter of the cookies weigh (2 - w)/4
One quarter of the cookies + tin = 0.8 = w + (2 - w)/4
Multiply through by 4; 3.2 = 4w + 2 - w
1.2 = 3w; w = 0.4