Okay, that little red box means that it’s a 90 angle soo that’s basically saying
3x= 90 so we gotta solve for x
3x=90
X=90/3
X= 30
Now that we know x we can solve for y in 2x + 3y (this equals 90 because they are complimentary angles Bc they add up to 180 and 90 is on the other side)
2(30) + 3y= 90
60+ 3y =90
3y= 90-60
3y = 30
Y=30/3
Y= 10