题目和答案都给你了，现在你要输出一个小学六年级能听懂的讲解，最好用苏格拉底的方式引导孩子思考。---4. (行程问题) 右侧扫码·视频讲解
两辆汽车从同一地点同时出发，沿同一方向同速直线行驶，每辆车最多只能带 20 桶汽油，途中不能用别的油，每桶油可使一辆车前进 60 公里，两辆车都必须返回出发地点，但是可以不同时返回，两车相互可借用对方的油。为了使其中的一辆车尽可能地远离出发地点，另一辆车应当在离出发地点多少公里的地方返回？离出发地点远的那辆车一共行驶了多少公里？ (6分)
Here is the extraction of the content from the image:
**Question 4**
**【解析】**
20 ÷ 4 = 5 (桶)
5 × 60 = 300 (公里)
20 ÷ 2 = 10 (桶)
10 × 60 = 600 (公里)
(300 + 600) × 2 = 900 × 2 = 1800 (公里)。
**【点拨】**
**Chart Description:**
Type: Line diagram representing movement paths.
Elements:
- A horizontal line segment with three points labeled A, B, and C from left to right.
- Point A is the starting point.
- Point C is the furthest point reached.
- Point B is located between A and C.
- Two horizontal arrows are drawn from A towards C, labeled "乙" (Yi) and "甲" (Jia). Both point to the right.
- Below these, a horizontal arrow is drawn from C towards A, labeled "乙". It points to the left.
- Above the main line, there is a dashed line path starting from the level of A, going right to the level of B, then turning back left to the level of B, and finally returning to the level of A. This path is associated with "甲". It shows movement from A to B (solid line with right arrow), then potentially returning towards A (dashed line with left arrow).
- Below the main line, there is a solid line path starting from A, going right towards C (labeled "乙" and points right). Another solid line path is drawn from the level of C returning left towards B (labeled "乙" and points left).
- Vertical dotted lines connect A, B, and C on the horizontal line to the movement paths above and below.
- The diagram is labeled "第4题图" (Figure for Question 4).
**Other Relevant Text:**
甲车行300公里停在B处，借给乙车5桶油，乙车继续前进20 ÷ 2 × 60 = 600 (公里)，返回B处，甲车再借给乙车5桶油，甲、乙两车返回出发点，乙车共行(300 + 600) × 2 = 1800 (公里)。
(Translation: Car Jia travels 300 kilometers and stops at point B, lends Car Yi 5 barrels of oil. Car Yi continues to advance 20 ÷ 2 × 60 = 600 (kilometers), returns to point B, Car Jia lends Car Yi 5 more barrels of oil. Car Jia and Car Yi return to the starting point. Car Yi travels a total of (300 + 600) × 2 = 1800 (kilometers).)