1. Proportions How do I solve a proportion?

12. Are these proportions equal? YES – they are equal!!

13. Are these proportions equal? YES – they are equal!!

14. Are these proportions equal? No – they are not equal!!

15. Now, let’s try something harder Sometimes, we will only know 3 of the 4 values in a proportion. The missing value is a VARIABLE. Take a look…. Z is the variable

16. Now, let’s try something harder When we have a variable, we can still cross-multiply. 10×5 = 50 1×Z = 1Z

17. Now, let’s try something harder What do you think we are going to do now? 10×5 = 50 1×Z = 1Z Write the cross products equal to each other.

18. Now, let’s try something harder What do you think we are going to do now? 50 = 1Z Write the cross products equal to each other.

19. Now, let’s try something harder What do you think we are going to do next? 50 = 1Z It is an equation so we are going to do the inverse - DIVIDE.

20. Now, let’s try something harder What do you think we are going to do next? 50 = 1Z It is an equation so we are going to do the inverse - DIVIDE. 50 ÷ Z = 50 so Z = 50

21. Let’s try again Solve for the variable: 8×15 = 120 4×X = 4X 4X = 120 120÷4=30 so X = 30

22. Here are some steps: 1.) Cross multiply. 2.) Write the cross-products equal to each other. 3.) Divide the number by itself by the number with the variable. 4.) Write your answer as x = …

23. Now You TRY

24. Summarize Answer the EQ: How do I solve a proportion?