What is wrong with following physics equations? (velocity and acceleration)

[Selfphysicslearner]

v_avg=(V_i+V_f)/2
v_avg=h/t
then v_avg*t=h
h=(V_i+V_f)/2 * t
V_f=at
(V_it+at²)*1/2=h
But formula on every resource I found says it should be;
(V_it+at²*1/2)=h
What mistake did I do ?

 

[cnh1995]

Vf=at

Is it?
Are you missing anything here?

 

[Dale]

Vf=at

This is not generally correct.

 

[Selfphysicslearner]

Is it?
Are you missing anything here?

I see it must be actually:Vf=Vi+at then there is 2 Vi in formula which eliminates 1/2 multiplied makes it
h=1/at^2 +2*1/2Vi

 

[Integral]

What are the fundamental units of acceleration?

 

[shivaprasadvh]

v_avg=(V_i+V_f)/2
v_avg=h/t
then v_avg*t=h
h=(V_i+V_f)/2 * t
V_f=at
(V_it+at²)*1/2=h
But formula on every resource I found says it should be;
(V_it+at²*1/2)=h
What mistake did I do ?

Vf=at , this equation means final velocity = acceleration * time. This can happen only if initial velocity is 0, but in the equation Vi is the initial velocity and Vi is not 0 as per the equations wrriten.