Respuesta :

The angle above the y is 90 degrees ( shown by the little square)

The 3 inside angles of a triangle need to equal 180.

Y = 180 - 90 - 48

Y = 42

Answer: y = 42°

Step-by-step explanation:

Triangle Sum Theorem states the sum of the angles of a triangle is 180°

y + 48° + 90° = 180°

y + 138° = 180°

y = 42°