(1)51.6÷[(3 2 5 -1.25)× 4 5 ],=51.6÷[(3.4-1.25)× 4 5 ],=51.6÷[2.15× 4 5 ],=51.6÷1.72,=30;(2)( 5 6 - 3 4 )÷( 1 4 + 1 6 ),= 1 12 ÷ 5 12 ,= 1 12 × 12 5 ,= 1 5 .