Solving:
The internal values of all triangles are worth 180°, so knowing this, just form a 1st degree equation to respond, remembering that the value 180°, will stay after the equal sign of the equation.
A)
[tex]\sf x+125^{\circ}+80^{\circ}=180\\\\\\\sf x+205=180\\\\\\\sf x=180-205\\\\\\\boxed{\sf x=-25^{\circ}}[/tex]
B)
[tex]\sf x+68^{\circ}+318^{\circ}=180\\\\\\\sf x+386=180\\\\\\\sf x=180-386\\\\\\\boxed{\sf x=-206^{\circ}}[/tex]
Okay?!
