The angles of a triangles are x°, 3x° and 30°. When asked to solve for x, Alvi shows the work in post-it A below. Brian shows the work in post-it B below. Who is correct and why? Why mistake did the incorrect person make?

that is the pic for post it a.
the post it b said

x + 3x + 30 = 180
4x + 30 = 180
4x = 150
x = 37.5

The angles of a triangles are x 3x and 30 When asked to solve for x Alvi shows the work in postit A below Brian shows the work in postit B below Who is correct class=