13x-5x=12.8
8x=12.8
x=12.8/8
x=1.6
x-2/5=1/3
x=1/3+2/5
x=5/15+6/15
x=11/15
2/9+x=7/15
x=7/15-2/9
x=21/45-10/45
x=11/45