Answer:
Clockwise
Step-by-step explanation:
Sorry I answered late
(It might also have helped immensely if you had been listening
when this was being explained in class.)
The first pipe fills 1/20 of the tank each minute.
The second pipe fills 1/30 of the tank each minute.
Operating together, the two pipes fill ( 1/20 + 1/30 ) of the tank each minute.
In order to add these fractions (or any fractions), you need a common denominator.
For these particular ones, ' 60 ' is a good choice.
( 1/20 + 1/30 ) = ( 3/60 + 2/60) = 5/60 = 1/12
The rate of work is 1/12 tankful per minute .
The most sensible choice for the time is 12 minutes.
R x T = W
( 1/12 tankful per minute ) x ( 12 minutes ) = 1 full tank
There are 6 other positions in the string, each with 26 choices. So if you fix BO as the first two letters, there are

possible strings that you can make.
If BO is at the end of the string, you still have

possible strings.
Together, then, you have

possible strings.
Answer:
Lesser than 6.9 minutes
Step-by-step explanation:
Let m represent the number of minutes of phone use with either plan A or plan B.
In plan A, the customer pays a monthly fee of $35 and then an additional 9 cents(9/100 = $0.09) per minute of use. This means that the total cost of m minutes would be
0.09m + 35
In Plan B, the customer pays a monthly fee of $55.70 and then an additional 6 cents(6/100 = $0.06) per minute of use. This means that the total cost of m minutes would be
0.06m + 55.70
Therefore, for the amounts of monthly phone use for which Plan A will cost less than Plan B, it becomes
0.09m + 35 < 0.06m + 55.70
0.09m - 0.06m < 55.70 - 35
0.03m < 20.7
m < 20.7/3
m < 6.9