Denis bought 50 postage stamps for which she paid $13.00. Some were 20-cent stamps and some were-40 cent stamps. How many of each did she buy? (Please show work with Substitution or Elimination Method)

Given a: b and b: c, find a: b: c. write the ratio in simplest form. a: b=6: 10 and b: c=21: 33

If y varies as x, and y=8 as x=4 what will be the value of y if x=2

Ms. lopez has 4 liters of chemicals that she is going to pour into beakers. each beaker will have 1/4 of a liter of chemicals, how many beakers can ms. lopez fill? draw a model to support your work. (it's ok if you dont)