Question

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Explanation:

Step1: Recall triangle - angle sum property

The sum of interior angles in a triangle is 180°. In the given right - triangle, one angle is 90° and another is 70°. Let the third interior angle be $y$. Then $y+90^{\circ}+70^{\circ}=180^{\circ}$.

Step2: Calculate the third interior angle

$y = 180^{\circ}-(90^{\circ}+70^{\circ})=180^{\circ}-160^{\circ}=20^{\circ}$.

Step3: Use the exterior - angle property

The exterior angle $x$ of a triangle is equal to the sum of the two non - adjacent interior angles. So $x = 90^{\circ}+70^{\circ}$.

Answer:

$160$