How do I find the equation of this line? (3D calc)

How do I find the equation of a line joining two points A=(1,2,3) B=(-1,2,5) :
a) In vector form
b) in symmetric scalar form
c) in parametric form

I think the text book I am using has different terminologies than my assignment and therefore has me confused. Thank you.

let's find the vector as

< -1 - 1 , 2 - 2 , 5 - 3 > ====> < -2 , 0 , 2 >

to find the line as having any of the two points:
<1 , 2 , 3 > + t <-2 , 0 , 2 > <======a


( x - 1 )/ -2 = (z - 3)/ 2 <===== b)



parametric form
x = 1 + -2t
y = 2
z = 3 + 2t