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monnettsavannah
you will do area for a triangle . when multiplying with the (x+9) you will just multiply the number infront of the parentheses by both the x and the 9. for example the 60 would be 60(x+9) which would be 60x+540
cheng12
60+x+9=2x then solve for x. x=69
plug in 69 to the exterior angle which is 2x. 2(69)=138°