SOLUTION: My son homework is on proportions. Example: If 2 adults are needed for every 15 students, how many students are needed for 180 students? 2 ? - = - 15 180 15?

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Question 11253: My son homework is on proportions. Example:
If 2 adults are needed for every 15 students, how many students are needed for 180 students?
2 ?
- = -
15 180
15? = 360
? = 24
First of all, can't I reduce...cancel out the 2 for a 1 and the 180 for 90. If I do then the number changes. Am I suppose to cancel out numbers? Why/why not?
Found 2 solutions by roxy9229, kyle491:
Answer by roxy9229(32) About Me  (Show Source):
You can put this solution on YOUR website!
2/15
x/180

you do 180 divided by 15 which is 12
so since 15 times 12=180, you do 2 times twelve which is 24

I wouldn't reduce because it might mix you up & it can get complicated

Answer by kyle491(5) About Me  (Show Source):
You can put this solution on YOUR website!
When setting up proportions you first need to set up what you know and what you dont.
You know that 2 adults are needed for 15 students so start setting up the proportion as: 2 over 15
Now you need to find out what you dont know: how many adults are needed for 180 students. So set up the proportion like you started to, putting the adults to students. You should have 2 over 15 equals X over 180.

Now we need to start the math. First cross mulitply the two numbers that you are able to, which are 2 and 180. You should come up with 360. Now, you divide 360 by the lonely number, 15. You should get X=12. 12 teachers are needed.
When doing proportions always remember to set up what you already know to what you need to know.