what did i do wrong in this equation?

I believe you just multiply the rate at which the bus slows down (19.6 m/s) by the amount of time it took for the bus to stop (23 s). The answer will be in meters.

(19.6 m/s) x (23 s)= 450.8 meters

I was about to break out the calculus, then realized it wasn't necessary. Because the slowdown is uniform (that is, you slow down by the same amount each unit of time), the answer is half the distance it would have gone if it didn't slow down at all.

original distance = 70.7km/h * 1hour/3600seconds * 1000m / km * 23seconds

= 452 meters

But since it slowed uniformly to a stop, the actual average speed was 35.35km/h. So you can divide the answer above by 2.

divide 70.7 by 3600 to convert to km/s then multiply by 23 , i got .4517km for distance

ahhh, i forgot it was slowing down

You need to use two formulas:

v = vi + a*t

x = xi + vi*t + a*t*t/2

You use the first one to calculate the acceleration (or deceleration in this case). Once you know the acceleration, you can plug it into the second formula, which you can use to find the distance traveled (x - xi). You should get:

a = -vi/t

x - xi = vi*t - (vi*t/2) = vi*t/2 = 225.4m