What is x? 5th Edition - Geometry Book 4, page 119, #6

[cbjohn1]

I don't understand the first of two explanations given for this problem.

I see the base of the triangle with the bold line as 12 and its height as 3, giving it an area of 18.

Next it says to setup an area of triangle function with a base of 7 and height of x (what we're solving for) and area of 18.

How can x be solved for using the area of the bolded triangle when x isn't even a part of the bolded triangle and is only a part of the larger part dash/bolded triangle?

[RonPurewal]

Hi,
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