In order for a fraction to be in simplest form, it must not be able to be simplified any more. In this case, this fraction isn't in simplest form because it still contains a decimal.
To get rid of this decimal, we should multiply this fraction by 5. However, because we want the ratio between the numerator and the denominator to stay the same, we must multiply both the numerator AND the denominator by 5.
1.4 / 7 * 5 / 5 = 7 / 35
However, 7/35 isn't in simplest form either, because they share a common factor of 7. So, to simplify more, we should divide both the numerator and the denominator by 7.
7/35 ÷ 7/7 = 1/5
Therefore, 1.4/7 in simplest form is 1/5.
