12.8 can be expressed as a fraction by writing the digits after the decimal point as the numerator and the place value as the denominator.
Since 12.8 is equivalent to 12 and 8 tenths, the fraction is 12/10.
To simplify the fraction, the numerator and denominator can be divided by their greatest common factor, which in this case is 2.
Therefore, 12/10 simplifies to 6/5.
So, 12.8 in simplest form as a fraction is 6/5.