Y is 7.5
A easy way to do it is simply graph it or divide it!
For instance, since x=5 is half of x=10, we would just divide 15 by 2 to get Y which is 7.5
Answer:
x = 11
Step-by-step explanation:
By intersecting chords theorem:

Is it definition of Congruence?
If you had 25 buttons ( red coloured) and 77 buttons (blue coloured). Half of the blue ones melted due to a supernova in the Atlantic ocean. Multiply red and blue buttons :)