Since a triangle is equal to 180 and both sides are equal that means you'll subtract 55 from 180 which is 125 then 125/2 which is 62.5 A straight line is equal to 180 so 180-105=75
Three has to be sane as angle above so 3 is 55. 4 is 75 because it needs to = 180 with the 105. Since 3= 55 and 4= 75 and all 3 must equal 180 45+75= 120 so 5 must be 60 because 180-120 = 60