Solve for d in the given triangle, where the angles are 90°, 45°, and d°.

The diagram shows a right-angled triangle, indicated by the square symbol, meaning one angle is $90^\circ$. The two short sides (legs) of the triangle are marked with single dashes, which means they are equal in length. This indicates that the triangle is an isosceles right-angled triangle.

In an isosceles triangle, the angles opposite the equal sides are also equal. Since the two legs are equal, the two acute angles must be equal. Let the unknown angle be $d$. Therefore, the other acute angle is also $d$.

The sum of the interior angles in any triangle is $180^\circ$.
So, we can write the equation:

Subtract $90^\circ$ from both sides:

Divide by 2:

Your calculation is correct. The value of $d$ is $\boxed{\text{45}^\circ}$.