Answer :
To concert a percentage into a fraction, first convert it into a decimal.
To change a percentage into a decimal, you have to take away the percentage sign and move the decimal point two places to the left.
Thus, 40% = 0.40 = 0.4
Now, to change the decimal into a fraction, you multiply both the numerator and the denominator (1) by 10.
0.4/1 = 4/10
However, in this case the fraction is in simplest form. To simplify a fraction, you have to divide the numerator and the denominator by the GCF, which in this case is 2.
4/10 = 2/5
Therefore, your answer is D. 2/5 off.