Respuesta :

choixongdong
<ABC + <ABC = 180
3x- 9 + 7x - 1 = 180
10x - 10 = 180
10x = 190
x = 19

<ABC = 3x- 9 = 3(19) - 9 = 48
sentthurskv
Hey there!

So let's take a look at those two angles... they seem to be supplementary, in other words the two angles add up to 180°.

Now lets set them up as an equation...

∠DBA + ∠ABC = 180                     Now substitute in the value of x into ∠ABC
(7x - 1) + (3x - 9) = 180                     (3x - 9)
(10x - 10) = 180                                 (3*19) - 9
10x = 190                                           57 - 9
x = 19°                                                48           <----- That's your answer!

I hope this helps! :D

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