The question asks, "Wie viel ergibt die Summe der Winkel a und b in diesem Dreieck?" which translates to "What is the sum of angles a and b in this triangle?"

From the image, we can see that the triangle is a right triangle. In a right triangle, one angle is always 90°. The sum of all angles in any triangle is always 180°.

Given that the third angle (the right angle) is 90°, the sum of the other two angles, a and b, must be: $a + b = 180^\circ - 90^\circ = 90^\circ$

Thus, the correct answer is 90°.

Would you like further details or explanations?

Here are 5 follow-up questions:

1. What is the sum of the angles in any triangle?
2. Can the sum of angles in a triangle be more than 180°?
3. How do we recognize a right triangle?
4. What is the measure of the third angle if angles a and b are both 45°?
5. How would you calculate angles a and b if you knew one of them?

Tip: In any triangle, the sum of all interior angles is always 180°.