1. 设标价为x元, x*80% = 188,x = 235(元)
2. 设第一个数x,则另一个数为8-x, x+3 = 8-x-3, 解得 x = 1,另一数为7
3. 设每小时行x千米,则有x*(9.5-8) = (10-8)*9 解得x = 12千米
4. 设孙子赢了x盘,则爷爷赢了8-x盘, 3x = 8-x 解得x = 2, 爷爷6盘
5. 设麦田为x, x*(1-0.25-(1-0.25)*0.2) = 6 解得 x = 10
6. 设其总寿命为x, 1/6x + 1/12x + 1/7x + 5 +1/2x + 4 = x
解得 x = 84
结婚时年龄 = 1/6x + 1/12x + 1/7x = 33
去世时 84