Answer:
Step-by-step explanation:
8x + 13y + 7 = 180 {Linear pair}
8x + 13y = 180 - 7
8x + 13y =173 -------------------(I)
9x - 7 + 13y + 7 = 180 {linear pair}
9x + 13y = 180 ----------------(II)
Multiply equation by (-1) and then add with equation (II). And thus y will be eliminated.
(I)* (-1) -8x - 13y = -173
(II) 9x + 13y = 180 {Now add}
x = 7
Plug in x = 7 in equation (I)
8*7 + 13y = 173
56 + 13y = 173
13y = 173 - 56
13y = 117
y = 117/13
y = 9
5y - 11 + z + 8x = 180 {Straight line angles}
5*9 - 11 + z + 8*7 = 180
45 - 11 + z + 56 = 180
z + 90 = 180
z = 180 - 90
z = 90
