What interval consists of all $u$ such that neither $2u$ nor $-20u$ is in the interval $(-\infty,-1)$ ?

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