No, this is not true, 22+32 =54 this is not a true statement
X - y + x + y = 180
2x = 180
x = 90
2x - 2y = x + y
x = 3y
y = x/3
y = 90/3
y = 30
x - y = 90 - 30 = 60
x + y = 90 + 30 = 120
2x - 2y = 180 - 60 = 120
(−7a − 19c) − (−12a + 30c) − (−21a − 11c)
= −7a − 19c + 12a - 30c + 21a + 11c
= (-7a + 12a + 21a) + (11c - 19c - 30c)
= 26a - 38c
= 2(13a - 19c)
