Combine like terms (-3y2 - 7y -9) - (4y2 + 6y + 9)

When combining like terms, find terms that have the same variable, same exponent or no variables and no exponents (coefficients).

So
-3y^2 and 4y^2
-7y and 6y
-9 and 9

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.