First turns those into fractions, now you should have 4/5 and 1/5. Now to generate a chance the 2 events will happen in a row (Like rain and a postponed game) you need to multiply the 2 fractions together so it should come out with 4/25 or 16%
The answer is 0.4375. What you do is you divide the top number (numerator) by the bottom number (denominator) when you want to turn a fraction into a decimal. So 7 divided by 16 is 0.4375.