nilai x....(cara nya juga perlu)

nilai x = 180 - y ( sejajar dg 45 derajat)
= 180 - 45
= 135

x + 55 = 135
x. = 135 - 55
x. = 80

45 + x + 55 = 180°
x + 100 = 180°
x = 180° - 100 = 80°