A and C are the correct answers.
Distance=speed times time
if they take the same time, we cal the time , t
b=bike speed
w=walking speed
bikedistnace=17=bt
walkdistance=9=wt
b is 4 more than w
b=4+w
we have
17=bt
9=wt
b=4w
ok so
multiply first equation by 9 and 2nd by 17
153=9bt
153=17wt
set equal
9bt=17wt
divide both sides by t
9b=17w
sub b=4+w for b
9(4+w)=17w
distribute
36+9w=17w
minus 9w both sides
36=8w
divide both sides by 8
4.5=w
he walks 4.5kph
The set of two-digit primes is {11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97}
Of that list, the following primes are mirror images of each other
13 and 31
17 and 71
37 and 73
79 and 97
Note: we ignore 11 since 11 flips to 11 which is not distinct from its original
If you're looking for the largest prime of this form, then its 97
If you're looking for the largest gap, then subtract each pair
31-13 = 18
71-17 = 54
73-37 = 36
97-79 = 18
We see that 71 and 17 have the largest gap
Answer:
B and C. can you select more than one?
