Compute the Laplace transform of the function ff on $[0,$$)[0,$$)$ defined by

f$($t$)=9$t$+6$f$($t$)=9$t$+6$

Give your answer as a function in the variable ss for s$>0$s$>0.$

L$($f$)($s$)=$L$($f$)($s$)=$