From the image, I see a quadrilateral with three known angles:

• One angle is $70^\circ$,
• Another angle is $100^\circ$,
• The third angle is also $100^\circ$.

The task is to find the fourth angle, which we'll call $x$.

In a quadrilateral, the sum of the interior angles is always $360^\circ$. So, we can use this fact to calculate $x$.

$70^\circ + 100^\circ + 100^\circ + x = 360^\circ$

Simplifying:

$270^\circ + x = 360^\circ$

Subtracting 270° from both sides:

$x = 360^\circ - 270^\circ = 90^\circ$

Therefore, the unknown angle $x$ is $90^\circ$.

Would you like a detailed explanation of how the sum of angles in a quadrilateral works? Let me know if you have further questions!

Here are 5 related questions to expand your understanding:

1. How is the sum of angles in a polygon calculated for shapes other than quadrilaterals?
2. What are some properties of quadrilaterals when one angle is $90^\circ$?
3. How can you classify quadrilaterals based on their angles?
4. What would change if the shape in the image were not a quadrilateral?
5. How can the properties of parallelograms or trapezoids apply to this kind of problem?

Tip: In any polygon, the sum of interior angles can be calculated using the formula $(n - 2) \times 180^\circ$, where $n$ is the number of sides.