How to solve inscribed quadrilateral problems: formula, example, and its solution.
In an inscribed quadrilateral,
there are two pairs of opposite angles.
(left figure, right figure)
For each pair,
the opposite angles are supplementary.
So m∠[blue] + m∠[green] = 180.
The given angles are the interior angles
of an inscribed quadrilateral.
These two angles are the opposite angles.
So x + 100 = 180
Move +100 to the right side.
Then x = 80.
These two angles are also the opposite angles.
So 70 + y = 180.
Move 70 to the right side.
Then y = 110.