i didn't listen when my teacher was showing us this as a review so i don't remember how to do it can someone give answer and explain if possible

X+y=-4 x-y=2 use elimination with adding and subtraction

Situation: find the age of the skull to the nearest year, enter the correct answer. a hiker in africa discovers a skull that contains 32% of its original amount of c- 14. done n = noekt 00000 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

27/9=18/x a. x=9 b. x=18 c. x=6 d. x=3