Understanding Proportions and Cross Multiplication

The video tutorial explains how to solve proportions by using cross multiplication. It covers the concept of proportions, where two ratios are equal, and demonstrates solving equations with variables n, z, r, and t. Each example involves setting up the proportion, performing cross multiplication, and solving for the unknown variable. The tutorial emphasizes the importance of isolating the variable and simplifying the equation to find the solution.

What is a proportion?

• A type of fraction

• A method to solve equations

• An equation stating two ratios are equal

• A comparison of two different units

Tags

CCSS.7.RP.A.2A

In a proportion, what is always true about the cross products?

• They are always equal

• They are always negative

• They are always different

• They are always zero

Tags

CCSS.6.EE.B.7

How do you solve the equation -28n = 336 for n?

• Subtract 28 from both sides

• Divide both sides by 28

• Multiply both sides by 28

• Add 28 to both sides

Tags

CCSS.7.EE.B.4A

What is the solution to the equation 14(z + 2) = 420?

• z = 34

• z = 28

• z = 30

• z = 32

Tags

CCSS.6.EE.B.7

What is the first step in solving 3r * 60 = 12 * 45?

• Divide both sides by 180

• Subtract 45 from both sides

• Multiply both sides by 180

• Add 60 to both sides

Tags

CCSS.3.OA.B.6

What is the value of r in the equation 180r = 540?

• r = 3

• r = 5

• r = 4

• r = 2

In the equation -10(-3t - 4) = -5(5t - 52), what is the first step?

• Add 52 to both sides

• Subtract 52 from both sides

• Distribute -10 and -5

• Add 4 to both sides

Tags

CCSS.6.EE.B.7

What is the solution to the equation 55t = 220?

• t = 5

• t = 4

• t = 3

• t = 2

Tags

CCSS.7.EE.B.4A

How do you isolate the variable term in the equation 55t + 40 = 260?

• Divide both sides by 40

• Multiply both sides by 40

• Subtract 40 from both sides

• Add 40 to both sides

Tags

CCSS.6.EE.B.7

What is the final step in solving a proportion with variables on both sides?

• Add the variables together

• Multiply by the coefficient of the variable

• Subtract the variables

• Divide by the coefficient of the variable

Tags

CCSS.6.EE.B.7