Step-by-step explanation:
angle S + angle W + angle STW = 180
(7x + 6) + (7x + 1) + angle STW = 180
So angle STW = 180 - (7x + 6) - (7x + 1)
angle STW + angle STP = 180 (straight angle = 180)
180 - (7x + 6) - (7x + 1) + angle STP = 180
angle STP = 180 - 180 + (7x + 6) + (7x + 1)
= 7x + 6 + 7x + 1
= 14x + 7
15x = 14x + 7
x = 7
angle STP = 15x = 15(7) = 105
