a/0.8+b/1.2=5/6(a/1.2+b/0.8)
5a/4+5b/6=5/6(5a/6+5b/4)
5a/4+5b/6=25a/36+25b/24 两边乘72
90a+60b=50a+75b
90a-50a=75b-60b
40a=15b
8a=3b
a/b=3/8
a/0.8+b/1.2=5/6(a/1.2+b/0.8)
5a/4+5b/6=5/6(5a/6+5b/4)
5a/4+5b/6=25a/36+25b/24 两边乘72
90a+60b=50a+75b
90a-50a=75b-60b
40a=15b
8a=3b
a/b=3/8