How to solve using cross multiplicationCreated by: Brittany and Andrea

Example 1.

• Solve:•

• 3(4x+5)=9(x+1)• 12x+15=9x+9• 3x+15=9

• 3x= -6

• X= -2The solution is -2. Check this in the original equation.

Steps: • Write original equation• Cross multiply• Distributive property• Subtract 9x from each

side• Subtract 15 from each

side• Divide each side by 3

Solve the equation by cross multiplying.

• You can do it!

Solve the equation by cross multiplying

• Solve: • = • 4(3x) = 9(x+2)• 12x = 9x+18• 3x=18 • X= 6

• Check your answer with the original equation.

• Rewrite the equation• Cross Multiply • Distributive Property• Subtract 9x from 12x.• Divide each side by 3.

Word Problem

• A long boarder travels 12 meters in the same amount of time that a second long boarder travels in 9 meters. The first long boarder travels 10.23 meters faster, every hour than the second long boarder. • A. Use this model to solve the equation: • =

Word Problem Worked Out

• = • 12(x)= 9(10.23)• 12x=92.07 • 92.07/ 12=x• X= 7.67

• X equals the speed of boarder 2.

• Fill in the equation with the correct numbers.• Cross Multiply• Distributive Property • Divide 92.07 by 12