原式=(0.7x11/13+0.7x11/9)-(6.6x5/3+3.4x5/3)
=0.7x(11/13+11/9)-5/3(6.6+3.4)
=0.7x11/22-5/3x10
=0.7x2-5/3x10
=1.4-6
=-4.6