AB=a just incase it cant be seen

Below

Step-by-step explanation:

● vector ED:

Vector ED = a since the Vectors ED and AB are colinear and have the same sense.

● vector CD:

Vector CD = -b since the vectors FA and CD are colinear but have opposite senses.

● Vector FB:

Vector FB = a+b

Using Chasles relation, we can express FB as the sum of the Vectors FA and AB.

● Vector BE:

Vector BE= -2b

The vectors BE and FA are colinear but have different senses. BE has a magnitude that is the double of FA's one.

●Vector EF:

Again using Chasles, relation we can express EF as the sum of the vectors FA and AB.

Vector EF= a+b

● Vector CF:

Vectors CF and AB are colinear but have opposite senses. The distance CF is the double of AB.

So: Vector CF=a+b

your question is incomplete, write all the numbers in the sequence that it tells you.  

step-by-step explanation: