What is 12 minus r what operation is being done write the expression

Either enter an exact answer in terms of \piπ or use 3.143.14 for \piπ and enter your answer as a decimal.

Yolanda wanted to buy a total of 6 pounds of mixed nuts and dried fruit for a party she paid 21.60 for mixed nuts and 11.90 for dried fruit did yolanda but enough mixed nuts and dried fruit for the party

Situation: an archaelogist in turkey discovers a spear head that contains 54% of its original amount of c-14. n = noekt no = inital amount of c-14 (at time t = 0) n = amount of c-14 at time t k = 0.0001 t = time, in years find the age of the spear head to the nearest year