pair of t.b. < 10 miles
a)1st and last are 25 miles
we don't know the number. maybe last is the second. then distance >10
maybe last is 25th and each pair s 1 mile apart. then distance <10
insufficient
b)total 4tb.
for every pair to be more than 10 mile apart, first and last booth should be 30 miles apart.
But they are only 25 miles apart
Thus atleast one pair <10 mile
IMO C

Hi,
From(1): We do not know how many toll booths are there. Not enough info. to tell
Insufficient
From(2): We do not know any distances.Not enough info. to tell
Insufficient
Both(1)&(2): Let the distances between successive toll booths be a,b,c
So, a+b+c = 25
At least one of a,b,c has to be less than 10.
Sufficient

Hence, C

P.S: Please write the question without using those short cuts. Wasted lot of time to understand that code language