Afarmer in china discovers a mammal hide that contains 70 of its original amount of c-14 n=noe^kt no=initial amount of c-14 at time t k=0.0001 t=time in years

N=N(sub o)e^-kt  

N/N(sub o)=e^-kt  

70/100=e^-kt  

ln .7=-.0001t  

t=ln .7/-.0001

ur welcome that is your Answer.

Step-by-step explanation:

well, because the $0.25 is an added cost depending on how many minutes, the answer would be y = 30 + 0.25x.