x
Then --------- at opening time. After 144 pineapple muffins were sold, the
2x/3 ratio became
x-144 3
--------- = ----
2x/3 5.
Let's solve this for x: 5(x-144) = 2x, or 5x - 720 = 2x. Thus, 3x = 720, and
x = 240.
There were 240 pineapple muffins in the beginning, and (2/3)(240) mango muffins (160).
After 144 pineapple muffings were sold, 240-144 represents the new count of the pineapple muffings. The new ratio of pineapple to mango is then
96 3
------ = ---- This tells us that our answer (240 pineapple muffins) is
160 5 correct.