What is the question itself?
-9-(-12)=-9+12=3
-9-12=-9+(-12)=-21
Answer:
They are identical triangles.
Step-by-step explanation:
Angles in a triangle add up to 180 degrees.
The triangle with 39 and 90 has a missing angle of 51 degrees, and the triangle with 51 and 90 vice versa.
Answer:
20x = 55
Step-by-step explanation:
First you have to add 3x to both sides of 11-3x=x

Now that you have 11 = 4x you divide 4 on both sides 
11/4 = x
But you can't divide 11 by 4 unless you are looking for the decimal form of 11/4 which is 2.75
so now we take 11/4 or 2.75 depending on if you need your answer in fraction or as a decimal and replace that with x however both will equal the number 55