Angle ABC and Angle DBC are adjacent angles.
What equation must always be TRUE?*
A. Angle ABC = Angle DBC
B. Angle ABC + Angle DBC = 90°
C. Angle ABC + Angle DBC = 180°
D. Angle ABC + Angle DBC = Angle ABD

c.

step-by-step explanation:

she should of added 9^2 and 12^2. that is because it is a^2+b^2=c^2. c^2 is the hypotenuse and should always be bigger than the other two numbers. which is why she should of added 9 squared and 12 squared together instead of 15 squared.

answer: x=60