1.8 in simplest form

1 8/10

reduce 8/10 by dividing by 2

8/2=4

10/2=5

1 4/5

mixed fraction into improper fraction

1 4/5

multiply the whole number with the denominator

1*5=5

Add 5 with the numerator = 5+4=9

Answer;

1 4/5 and 9/5

1.8 in fraction form (simplest) is 1 4/5 or 9/5