<image>Xiaoming bought several kilograms of watermelons from a wholesale market at the price of ¥0.8 per kilogram during his summer social practice activity, and then sold them at a market. After selling 40 kilograms of watermelons, the price per kilogram was reduced by ¥0.4, and all were sold out. The relationship between the sales amount and the number of kilograms of watermelons sold is shown in the figure. Based on the information provided in the graph, please complete the following problems:


(1) Find the relationship equation between the sales amount \( y \) (yuan) and the number of watermelons sold \( x \) (kilograms) before the price reduction;
(2) How many kilograms of watermelons did Xiaoming buy from the wholesale market in total?
(3) How much profit did Xiaoming make from selling the watermelons this time?