1. Since there are 2 intersecting straight lines, and you know that one angle is 35°, the angle on the opposite side (aka Angle A) must also be 35°!
2. All 3 angle measurements in a triangle MUST add to 180°, and we know that one angle is 90°, and another is 35°. Angle B=180°-(90°+35°)=180°-125°=55°.
3. Like I explained before, when there are 2 intersecting straight lines, the opposite angles will be equal. Therefore Angle C is equal to Angle B which is equal to 55°.
Answer: Angle A=35°, Angle B=55°, Angle C=55°