1－（5/7+3/14÷3/4）×2/7
= 1 - ( 5/7 + 3 / 14 × 4 / 3 ) × 2 / 7
= 1 - ( 5 / 7 + 4 / 14 ) × 2 / 7
= 1 - ( 5 / 7 + 2 / 7 ) × 2 / 7
= 1 - 1 × 2 / 7
= 1 - 2 / 7
= 5 / 7