（1）5/7×53+1/7×85
=5/7×53+5/7×17
=5/7×（53+17）
=5/7×70
=50
（2）6×11/8＋4÷8/11--11/8×5
=6×11/8-11/8×5＋4×11/8
=11/8×(6-5+4)
=55/8