You can solve ratio and proportion problems with cross multiplication

a/b = c/d
(a/b) * b * d = (c/d) * b * d
a * d = c * b

You can freely convert between fractions, decimals and percents

4% = 4/100 = 0.04
0.49 = 49%
1/4 = 0.25 = 25%
"Find 6% of 99" = (6/100) * 99 = 5.94