ABCD is a parallelogram. If angle A is equal to 45°, then find the measure of its adjacent angle.

135°

Properties of parallelogram:

1. Opposite angles are equal
2. Adjacent angles are supplementary  
3. The sum of interior angles of a parallelogram is equal to 360°
4. The consecutive angles of a parallelogram should be supplementary

As adjacent angles are supplementary thus, the measure would be 180° - 45° = 135°.