Answer:
5?
Step-by-step explanation:
You start from negative -1 and you got all the way to 4, so the distance in-between the objects are 5
(a+a+6)*2.5=345
2a+6=138
a=132/2
a=66 mph
a+6=66+6=72 mph
Speed of the first car is 72 mph
1.95 = .21(5) + .06m
1.95 = 1.05 + .06m
Solving (if needed)
Subtract 1.05 from each side
1.95 - 1.05 = .06m
.90 = .06m
Divide .06 on both sides
15 = m