Please show me how to do this

Question

Find the measure of the obtuse angle.

(5y-48)(3y+60)

The obtuse angle measures   degrees.

Answer 1

There are 2 vertical angles 5y-48 and 3y+60.

set up a equation 5y-48 + 3y + 60 = 180

solve for y

y = 21

5(21) - 48 = 57

3(21) + 60 = 123 (obtuse angle)

Answer 2

I'm assuming the too angles are the supplementary angles:

5y-48 = 3y+60 group y terms and constant terms

2y = 108

y=54

Plug y into the two expressions. The angle greater than 90 is the answer.