You have piano lessons every 4th day and guitar lessons every 6th day. today you have both lessons. in how many days will you have both lessons on the same day again? explain?

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