Kinematics... please help

hey guys i got my maths exam in two days and need urgent help in the kinematics area.

i get some of the basic stuff but anyways the question i'm struggling with is

**Particle moves in a straight line so its position x cm relative to O at time t seconds (t≥0)**

is given by x=t**²-7t+12**

FIND

a. initial position

*t=0*

so therefore x=**0**²*-7(0)+12*

x=12 cm to right of O

b. position at t=5

*so therefore*

x=5*²*-7(5)+12

x=25-35+12

x=2 cm to the right of O when t=5

** c. initial velocity**

d. when and where velocity = 0

e. average velocity in the first 5s

f. average speed in the first 5s

alright the ones in red are the ones im sturggling with

anyone help would be greatly appreciated... thanks a lot guys and girls