Xiaolan's mother bought several bottles of yogurt for 12.5 yuan in the supply and marketing building, but she found in the food optional room of the department store that the same yogurt was 0.2 yuan cheaper than each bottle in the supply and marketing building. Therefore, when she bought yogurt for the second time, she went to the Department store to buy it. As a result, she spent 18.4 yuan and bought 3 / 5 more bottles than the first time. How many bottles of yogurt did she buy in the supply and marketing building for the first time?

Xiaolan's mother bought several bottles of yogurt for 12.5 yuan in the supply and marketing building, but she found in the food optional room of the department store that the same yogurt was 0.2 yuan cheaper than each bottle in the supply and marketing building. Therefore, when she bought yogurt for the second time, she went to the Department store to buy it. As a result, she spent 18.4 yuan and bought 3 / 5 more bottles than the first time. How many bottles of yogurt did she buy in the supply and marketing building for the first time?

Suppose: the first time I bought x bottles of yogurt. The second time I bought x + 3 / 5x = 1.6x bottles of yogurt
12.5/x = 18.4 / 1.6x + 0.2 multiply both sides by X and 1.6x to get:
20x = 18.4x + 0.32x square, divide each term by X to get:
20=18.4+0.32X 0.32X=20-18.4
0.32x = 1.6 x = 5 bottles
A: I bought 5 bottles of yogurt for the first time