rearranging basically what you do too one side the opposite applies..
v=u+at
to rearrange for a
v=u+at (to get u to the other side, since its a PLUS, MINUS it)
v-u=at (since these two are MULTIPLY, DIVIDE one)
(v-u)/t=a
now for a more complicated one, eg
s=ut+1/2at^2
lets say we rearrange for a again BUT
s=10
u=0
A=9.81
T=?
it immediately gets rid of ut, as 0*anything = 0 which is very common in both projectiles and kinematics so:
s=1/2at^2 (do the opposite of halve, times by 2)
2s=at^2 (divide by a)
2s/a=t^2
then sub in
2*10 = 20
20/9.81 = 2.04 so t^2 = root 2.04 = 1.43
ermm dunno if that would of helped or not but thats the best i can do to help, i used to struggle with rearrangments, just remember, to get one thing to the other side, do the opposite!