2/7+x=6/7.
x=6/7-2/7
x=4/7
3x-4=0.5.
3x=0.5+4
x=4.5÷3
x=1.5
x-1/8-4/15=1/3
x-47/120=1/3
x=1/3+47/120
x=29/40