Solving Systems of Equations with Trolls and Tolls

In a fantasy land, you must cross a bridge guarded by a troll to reach a castle. The troll demands a $5 toll, but you have no money. Instead, he offers a riddle: determine the number of $5 and $10 bills he has, given he has 900 bills totaling $5,500. The video guides you through solving this problem using algebra and systems of equations.

What is the main objective of the traveler in the fantasy land?

• To explore the forest

• To defeat the dragon

• To save the princess or prince

• To find a hidden treasure

Why can't the traveler swim across the river?

• The river is too cold

• The river is very rough

• The river is too wide

• The river is full of dangerous creatures

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CCSS.RI.1.1

CCSS.RI.2.1

CCSS.RI.3.1

CCSS.RL.2.1

CCSS.RL.3.1

What does the troll initially ask for to allow crossing the bridge?

• $20

• $10

• $15

• $5

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CCSS.RI.6.10

CCSS.RI.7.10

CCSS.RI.8.10

CCSS.RI.9-10.10

CCSS.RL.7.10

What alternative does the troll offer since the traveler has no money?

• A physical challenge

• A riddle

• A puzzle

• A race

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CCSS.RI.6.10

CCSS.RI.8.10

CCSS.RI.9-10.10

CCSS.RL.7.10

CCSS.RL.9-10.10

What are the two types of bills the troll accepts?

• $5 and $20

• $5 and $10

• $1 and $5

• $10 and $20

What variable is used to represent the number of $5 bills?

• f

• x

• t

• y

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CCSS.6.EE.C.9

What is the total number of $5 and $10 bills the troll has?

• 800

• 900

• 1000

• 1100

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CCSS.8.EE.C.8C

How is the total value of the troll's money represented?

• $5500

• $6000

• $5000

• $4500

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CCSS.6.EE.B.6

What is the value of each $10 bill?

• $15

• $20

• $10

• $5

What mathematical concept is introduced to solve the troll's riddle?

• Probability

• System of equations

• Inequalities

• Quadratic equations