Answer:
x=21°
Explanation:
Angle A = Angle B
Angle A = 45°
2x+3 =45°
To work out what x is, you would have to do inverse operations.
45-3=42°
2x=42°
42÷2=21° (We divide by 2 because, in algebra, whenever a number is next to a letter, it means times, so then we have to do the opposite and divide).
So, x=21°
Hope this helps :)