Write the dimensions of the a and b in the equation v=a+bt where v is velocity and t is time
we follow the rule : when we add or subtract some terms, all these terms should be of the same dimensions to which they are equated.
so, [a] = [v]
[a] = [LT-1]
and,
[bt] = [v]
[b] [T] = [LT-1]
[b] = [LT-2]