the deceleration of a particle moving in a straight line with speed v has magnitude 2e^v .It's initial speed is 10 m/s

(i)find the time t1 for the speed to half in magnitude.

(ii)find the time t2 for the particle to come to rest.

(iii) deduce (t2-t1)/t1 =e^5

I can not do any of this question.

I am letting dv/dt = -2e^v I am having trouble seperating this and I do not know how to integrate it.