Answer:
72 mi is the answer.
Step-by-step explanation:
a = 30 mi
b = ?
c = 78 mi
According to the Pythagoras theorem,
a² + b² = c²
30² + b² = 78²
900 + b² = 6084
b² = 6084 - 900
b² = 5184
b = 72 mi
∴ the eastbound airplane has travelled 72 mi.
