You do it the way you change any percentage to a fraction. Divide by 100% and simplify.

66 2/3%

= (66 2/3%)/(100%)

= (200/3)/100

= 200/300

= (2*100)/(3*100)

= (2/3)*(100/100)

= (2/3)*1

66 2/3%

= (66 2/3%)/(100%)

= (200/3)/100

= 200/300

= (2*100)/(3*100)

= (2/3)*(100/100)

= (2/3)*1

**= 2/3**