How do I do highlighted questions with working (only answering one is fine) picture below

Answer of 8:
x= 25°
Step-by-step explanation:
As we can see in the figure given that BAC is a right angled Triangle
Now from simple rules of geometry we know that
Sum of all the angles of a triangle= 180 ⁰ ................. (i)
Now it is given to us that
∠BAC=(2x-5)°
∠ACB=(2x+15)°
and
∠ABC=90°
Now from equation (i) we know that
∠ABC + ∠BAC + ∠ACB =180° ........... (ii)
putting the values in equation (ii)
(2x-5)° + (2x+15)° + 90° = 180°
2x - 5° + 2x + 15° + 90° =180°
simplifying it will gives
4x + 80° = 180°
4x = 180° - 80°
4x = 100°
cross multiplying gives
([tex]x=\frac{100}{4}[/tex])°
which gives us
x= 25°