Insufficient information?

Its a word problem at grade 11 level, which is probably really easy to most of you guys (and girls), but I can't find the angles VTR and VRT, which I am assuming are needed to complete this question. Well, here is is:

Two fire towers are located 100km apart on high hills T and R. The bearing from T to R is north east. A fire F is observed from tower T at N10 E and from tower R at N75 W. The town of Pretty Valley, at point V, is on a bearing of N25 E from tower T and S70 W from R. The observers report the wind is blowing the fire directly toward Pretty Valley at a rate of 8km/h. How many hours do the officials have to evacuate the town?

Thanks in advance!