Analysis: I borrowed 500 yuan from my father and 500 yuan from my mother. After paying back the money, I owe my father 490 and my mother 490. You should add the returned 20 Yuan You, which is 1 ,000 yuan, not the remaining 10 yuan. The logic is wrong, so the calculation is wrong.

Solution: First, I borrowed 500 yuan from my father, 500 yuan from my mother, bought a pair of shoes, spent 970 yuan, and left 30 yuan. The money here is still right. I returned 10 yuan to my father, 10 yuan to my mother, and there was 10 yuan left. The money here is also right. I still owe my father 490 yuan and my mother 490 yuan. But if you work out 490+490+ your own 10 yuan =990 yuan, it's wrong. 490+490 = 980 yuan shows that you still owe them so much, because you have already paid back 20 yuan, and you should pay back 980+20= 1000 yuan; Your remaining 10 yuan should be calculated as follows: you spent 970 yuan and gave each parent 10 yuan, that is, the remaining 10 yuan in 20 yuan, 970+20+ 10 = 1000 yuan.

Setting 490+490+ 10 is unreasonable.