How to solve this 9:n=12:4?

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Answer 1 · 2018-05-16T19:57:02

n = 3

What we have here is a ratio. We can use the means-extremes property of proportions to solve this.

The means-extremes property of proportions states that if #a/b = c/d#, which is the same as #a:b = c:d#, then #ad = bc#

So, lets assign values to these variables in the formula:
#Let: a=9, b=n, c=12, and d=4#
This gives us the equation: #9/n=12/4#

To solve, we cross multiply first, giving us: #9 times 4 = 12 times n#

Simplifying gives us: #36 = 12n#

Now we divide both sides by twelve to get n by itself: #36/12 = (12n)/12#

We simplify one last time to get: #3 = n#