Answer fast?!??
Study the figure below

[tex]180 = 50 + 45 + b \\ 180 = 95 + b \\ 180 - 95 = b \\ b = 85[/tex]
[tex]180 = 75 + a + b \\ 180 = 75 + 85 + a \\ 180 = 160 + a \\ 180 - 160 = a \\ a = 20[/tex]