Answer:
92 mph
Explanation:
Let the speed of the van travelling south 
= 
v 
 mph 
 
The distance travelled by the car travelling north is 
 
d 
1 
= 
10 
⋅ 
2.5 
= 
25 
 
The distance travelled by the car travelling south is 
 
d 
2 
= 
v 
⋅ 
2.5 
= 
2.5 
v 
 
The distance between the cars after 
2.5 
h 
 is 
 
d 
1 
+ 
d 
2 
= 
255 
 
25 
+ 
2.5 
v 
= 
255 
 
2.5 
v 
= 
255 
− 
25 
= 
230 
 
v 
= 
230 
2.5 
= 
92 
 mph 
 
The speed is 
= 
92 
 mph