Answer:
a
 the displacement of the plane is 

b
 The displacement of plane from Portland to Akron with layover at Houston is 
 
 
 
c
 the vector which defines this displacement is 

Explanation:
From the question we are the 
 The displacement from Portland, Oregon to Houston, Texas. is 

 The displacement from Houston, Texas to Akron, Ohio. is 
 a
a
a 
 The motion of the plane in question a is in the opposite direction to vector 

So the displacement of the plane is 

b 
The motion of Portland to Houston to Akron is in the direction of both vector 
 and
 and 
 so
 so 
 The displacement of plane from Portland to Akron with layover at Houston is 
 
 
 
c
 From the question we are told that the plane flies over Portland to get to Anchorage, Alaska which implies that it is moving in opposite direction to the vector 

 Give that distance from Portland to Houston is 

 and the distance from Portland to Anchorage is 
 km
km
Then the vector which defines this displacement is mathematically represented as 
 

 
