8.2＋1.8÷2.5－1.5×0.6 怎样简算,4又6分之一减x等于2又5分之3怎样解方程!急,好心人求助

=8.2+1.8*0.4-1.5*0.6
=8.2+1.8*0.4-1.5*（0.4+0.2）
=8.2+1.8*0.4-1.5*0.4-1.5*0.2
=8.2+（1.8-1.5）*0.4-1.5*0.2
=8.2+0.3*0.4-1.5*0.2
=8.2+0.3*2*0.2-1.5*0.2
=8.2+0.6*0.2-1.5*0.2
=8.2-（1.5-0.6）*0.2
=8.2-0.9*0.2
==8.2-0.18
=8.02
4又1/6-x=2又3/5
x=4又1/6+2又3/5
x=6又23/30