Given that 4/5 of a number is 16 find 75% of the number

Simplify each expression. use positive exponents. show work . (x –2 y –4 x 3 ) –2

Can anyone me get through my algebra 2 class? the only class i need to graduate..

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