There were 104 cookies in a box. The number of raisin cookies was 6/7 the number of plain cookies. Trisha ate an equal number of raisin and plain cookies. As a result, the ratio of the number of raisin cookies to the number of plain cookies left was 3:5. How many raisin cookies were left in the end?
+23 Hi!
If we say that x is the number of plain cookies, then 6x/7 is the number of raisin cookies. If we add x and 6x/7, we get 13x/7.
13x/7 = 104
13x = 728
x = 56
We have 56 plain cookies and 48 raisin cookies. Now we need to take a certain number away from both of these numbers to get a ratio of 3:5.
(48- x)/(56 - x) = 3 / 5
(48- x)5 = (56 - x)3
240 - 5x = 168 - 3x
72 = 2x
36 = x
Now that we have this number, we can find out that there are 48 - 36 = 12 raisin cookies left.
