x=5a+3=7b+6=9c+7
=5(a+19)-92=5m-92
=7(b+14)-92=7n-92
=9(c+11)-92=9p-92
x+92=5m=7n=9p
所以x+92是5,7,9的公倍数,最小为5*7*9=315
x最小为315-92=223