To get a fraction into a decimal, divide the numerator (the top of the fraction) by the denominator (the bottom). In this case, do 6 divided by 20.
You can also think the division bar (/) as "divided by." So 6 divided by 20.
6 divided by 20 = 0.30
To get a decimal into a percent, multiply by 100 (move the decimal point two places to the right). Then put % at the end.
0.30 = 30%