Need help asap please and thank you

Renita analyzed two dot plots showing the snowfall during the winter months for city a and for city b. she found that the median snowfall is 5 inches less in city a than in city b. the mean snowfall is about 2 inches less in city a than in city b. which explains why there is a difference in the measures of center for the sets of data?

When you answer this can you explain

How to use order of operation in 20 divide by 4 multiply 5 = 1