Answer:
rational number is the. answer trust me
In a question like this, you want to approach it with the equation "slope intercept form" which is

b = y-intercept
- the point where the line intercepts the y-axis
m = slope
I suggest using Desmos Graphing Calculator, it really helps and shows you a graphed equation. Let me know what you get!
Answer:
AE/AB = EF/BC
4cm/ 8cm = EF/ 5cm.....(Criss cross)
EF = 5 x 4/8
EF = 2.5 cm