Answer: d = 29 miles
Step-by-step explanation:
S11°W = 259° on a unit circle
N75°E = 15° on a unit circle
x separation after two hours
x = 2(8cos15 - 18cos259) = 21.179 miles
y separation after two hours
x = 2(8sin15 - 18sin259) = 19.7398 miles
total distance between them is
d = √(19.7398² + 21.179²) = 28.9518... ≈ 29 miles