First, write the numbers 0.17 and 0.128 as a fraction. To do so, remember that if the denominator is not visible, we can consider it as equal to 1:
Multiply both numerator and denominator by 1000:
Since both 128/1000 and 170/1000 have the same denominator, we can find another fraction between both of them just by finding a number between the numerators. This is, a number between 128 and 170.
Since 128<150<170, then a fraction between 128/1000 and 170/1000 is:
Therefore: