You can recognize that the digit 8 is in the tenths place, so the number represents 98 tenths, or
98/10 = 49/5 (49/5 is the reduced form of the fraction)
As a mixed number, it is
9.8 = 9 8/10 = 9 4/5
98/10 = 49/5 (49/5 is the reduced form of the fraction)
As a mixed number, it is
9.8 = 9 8/10 = 9 4/5