A particle moves along a straight line 𝑂𝑋. At a time 𝑡 (in seconds) the distance 𝑥 (in meters) of the particle from 𝑂 is given by 𝑥 = 40 + 12𝑡 − 𝑡 3 How long would the particle travel before coming to rest

Question : A particle moves along a straight line 𝑂𝑋. At a time 𝑡 (in seconds) the distance 𝑥 (in meters) of the particle from 𝑂 is given by 𝑥 = 40 + 12𝑡 − 𝑡 3 How long would the particle travel before coming to rest