1/6+x=5/7解：x=5/7-1/6x=30/42-7/42x=23/42
解方程得1/6+x=5/7x=5/7-1/6x=30/42-7/42x=23/42
1/6+x=5/7x=.5/7-1/6=30/42-.7/42, =23/42
