Something

TABLE `people` (
  `id` int
  `name` varchar
  `money` int
) 

INSERT INTO `people` 
(1, 'name1', 500),
(2, 'name2', 80),
(3, 'name3', 1250),

TABLE `bag` (
  `id` int
  `user_id` int
  `item` varchar
  `price` int
)

INSERT INTO `bags` 
(1, 3, "item1", 120),
(2, 3, "item2", 100),

SELECT d.id, d.name, d.money, sum( dl.price) AS buying, d.money- sum( dl.price) AS actual_money
FROM people d, bags dl
WHERE d.id = dl.user_id
GROUP BY d.id