Hello!
The arcs in both angles A and D mean they are equal to each other
5y + 11 = 12y - 10
Now you solve it algebraically
Add 10 to both sides
5y + 21 = 12y
Subtract 5y from both sides
21 = 7y
Divide both sides by 7
3 = y
Put this into the equation for angle A
angle A = 5(3) + 11
Multiply
angle A = 15 + 11
Add
angle A = 26
The answer is 26°
Hope this helps!
