Expand the expression.
-7 (6 - 3)
-k - 21
-7k + 21
-7k - 21
k + 21

The major difference is that a histogram is only used to plot the frequency of score occurrences in a continuous data set that has been divided into classes, called bins.  bar charts, on the other hand, can be used for a great deal of other types ofvariables  including  ordinal  andnominal  data sets.