need help. The skier goes down the slope distance d and time t. The relationship between d and t can be represented in the following form

d = at = bt^2
where a nd b are constants.
If given d=11 t=2 and d=28 t=4 how to calculate values of a and b. Calculate the length of the slope corect to the nearest metre, if the skier riches the bottom in 11 seconds.