First a triangle adds up to be 180 degrees total.
So with the first triangle you add 75 + 50 = 125. Then next step is you do is 180-125=55. m<c equals 55 degrees. Acute angle
Then with the triangle in the middle you add 60+30=90. Then next step is you do is 180-90=90. m<b equal 90 degrees. Right angle
Last triangle you add 45+30=75. Then next step is you do is 180-75=105. m<a equals 105 degrees. Obtuse angle
