Amanda sells t-shirts at a market for $15 each. her costs are $6 per t-shirt and $540 per month rent. how many t-shirts must amanda sell per month to equal her monthly costs?

Use the equation 
15t = 6t + 540
t = t shirts
i'm not sure though, I could be wrong sry 

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.