设百位数是 x ,则 十位数是 x + 5 ,个位数是 2x
x + x + 5 + 2x = 17
4x + 5 = 17
4x = 17 - 5
4x = 12
x = 12÷4
x = 3
百位 = x = 3
十位 = x + 5 = 8
个位 = 2x = 6
所以这个三位数是 386