standard_description: Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles. For example, arrange three copies of the same triangle so that the sum of the three angles appears to form a line, and give an argument in terms of transversals why this is so.
problem_activity: Problem 1
Represent each fraction as a percent by completing the table. Use the two double number lines below to show your work.
| Fraction |   |   |   |   |   |
|----------|---|---|---|---|---|
| Percent  |   |   |   |   |   |
[IMG]
Problem 2
Answer the questions below using mental math. Use your double number lines from Anchor Problem 1 if you need to.
a.   What is
$$\frac{1}{2}$$
of 20?
b.   What is 50% of 20?
c.   What is 10% of 60?
d.   What is 20% of 60?
e.   What is
$$\frac{1}{4}$$
of 48?
f.   What is 25% of 48?
g.   What is 75% of 48?
h.   What is 10% of 125?
i.   A textbook that costs $36 is on sale for 25% off. How much money will you save?
Problem 3
Answer the questions below using mental math. Use your double number lines from Anchor Problem 1 if you need to.
a.   5 is 50% of what number?
b.   12 is 10% of what number?
c.   15 is 25% of what number?
d.   30 is 75% of what number?
e.   400 is 20% of what number?
f.   A coat is on sale for 10% off. You save $18. What was the original price of the coat?
Problem 4
Answer the questions below using mental math. Use your double number lines from Anchor Problem 1 if you need to.
a.   24 is what percent of 240?
b.   350 is what percent of 700?
c.   20 is what percent of 80?
d.   30 is what percent of 40?
e.   80 is what percent of 80?
f.   You saved $4 on a book that originally cost $16. What percent of the original cost did you save?


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