.
In case (a), x + (4x-30) = 90 degrees.
In case (b), x + (4x-30) = 180 degrees.
You do the rest.
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At this point, I completed my instructions.
On complementary/supplementary angles and millions associated solved problems (your templates) see the lessons
- Angles basics
- HOW TO solve problems on supplementary, complementary or vertical angles - Examples
in this site.
Learn the subject from there (!)