X进制的数47 = 4X + 7 ,X>7
Y进制的数74 = 7Y + 4,Y>7
则有
4X + 7 =7Y + 4
4X = 7Y - 3 = (4Y-4) + (3Y+1)
X = (Y-1) + (3Y+1)/4
显然3Y+1能被4整除,且Y>7.则Y最小为9,
此时X最小为15
综上,X+Y最小为15+9=24
X进制的数47 = 4X + 7 ,X>7
Y进制的数74 = 7Y + 4,Y>7
则有
4X + 7 =7Y + 4
4X = 7Y - 3 = (4Y-4) + (3Y+1)
X = (Y-1) + (3Y+1)/4
显然3Y+1能被4整除,且Y>7.则Y最小为9,
此时X最小为15
综上,X+Y最小为15+9=24