In 5-card poker, a straight is five cards of consecutive denominations (not all the same suit). how many ways are there to get a straight?

Straight in one suit may be such:

A,2,3,4,5
2,3,4,5,6
3,4,5,6,7
4,5,6,7,8
5,6,7,8,9
6,7,8,9,10
7,8,9,10,J
8,9,10,J,Q
9,10,J,Q,K
10,J,Q,K,A,

totally for one suit 10 ways of forming straight. You also have 4 suits (Club, Hearts,...), so you can choose each card from four possible suits and can form 4^5·10=10240 straights in all suits.

10240 ways to get a straight

If you divide 0.1 and 0.6 you wii get 0.166666 which rounds to .167 which is answer b