standard_description: Understand solving an equation or inequality as a process of answering a question: which values from a specified set, if any, make the equation or inequality true? Use substitution to determine whether a given number in a specified set makes an equation or inequality true.
problem_activity: Problem 1
Read each situation below and then answer the questions that follow.
Situation A:
In the spring, an animal shelter had 216 animals. By the end of the summer, this number decreased by 8%. How many animals were at the shelter at the end of summer?
Situation B:
After advertising for adoptions on local television, an animal shelter decreased the number of animals at the shelter by 8%. There are now 216 animals. How many animals were at the shelter before the advertising?
a.   Sketch a visual diagram to represent each situation.
b.   How are the two situations similar?
c.   How are the two situations different?
Problem 2
A store sells backpacks in two sizes: small and large. The large backpacks sell for 20% more than the smaller backpacks. If a large backpack costs $75, how much does the small size cost?
Draw a visual representation of the situation, and then use an equation to solve.


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