1. F(n)= # of positive numbers less than n which have no common factor with n besides 1
Lets try a few cases
f(6)=5,4,2=3 (3 is not a part of this as 3 is a factor of 6)
f(8)=7,5,3=3 (2 and 4 is not a part of this as they are factors of 8)
f(14)=13,11,9,7,5,3=6

Since, p is prime number let us try f(n) with a few prime numbers
f(17)= 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2=15
f(11)= 10 9 8 7 6 5 4 3 2 = 9
f(13)= 12 11 10 9 8 7 6 5 4 3 2=11

From these 3 examples we can infer that for prime numbers f(n)=n-2
Hence, f(p)=p-2 Hence [spoiler]B
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Thanks for your answer, but the right answer is A. p-1
So I don't know how to do it right

2. In the city, the car averages 25 mpG and it is to be driven 10 miles in the city
By cross multiplying we can figure that:
If one gallon gives you 25 miles, then for 10 miles one would need 10/25=0.4 Gallons.....(1)


On the highway the car averages 40 mpG and it is to be driven 50 miles on the highway
By cross multiplying we can figure that:
If one gallon gives u 40 miles, then for 50 miles you'd need 50/40=1.25 Gallons.....(2)

Total volume of gasoline spent=0.4+1.25=1.65 Gallons
Total Distance traveled is 10 miles in the city+50 miles on the highway=60 Miles

Again, by cross multiplying if 1.65 Gallons gives you 60 miles then 1 Gallon would give you

60/1.65 miles=36.36 ≈36 Hence, D