We know that the whole angle of the triangle is 73. Since the known angle is 45 degrees, we need to find out what the other is.
Subtract 45 from 73 to find the angle of the unknown triangle.
73-45=28.
Now that we know the value of the unknown triangle, solve for x
Make an equation.
2x+5=28
Subtract 5 on both sides.
2x=23
Divide 23 by 2 to isolate x.
X=11.5
The answer is C. 11.5
Hope this helps!
