Hey just had a problem regarding rates of change.

ill post the whole question so there is no confusion.

" The number of bacteria present in a culture at time t hours after the beginning of an experiment is denoted by N. The relationship between N and t is modelled by N=10(1+3/2t)*3 (that is 10 multiply 1 plus 3 over 2 t to the power of 3) At what rate per hour will the number of bacteria be increasing when t=6?

im assuming the chain rule must be used but i cant find the other differential i need to use... any help would be greatly appreciated

thanks