Answer with Step-by-step explanation:
We are given that A,B,C,D,E and F.
We have to find the number of different four -letter arrangements can be formed using given six letters a,if the first letter must be C and one of the other letters must be B and no letter can be used more than once in the arrangement.
Number of letters=6
We have to arrange four letter out of six
After fixing C and B then we choose only two letters out of remaining four letters and repetition is not allowed.
Permutation formula :
We have n=4 an r=2
Using this formula and substitute the values
Then, we get 

Hence, number of different four -letter arrangements can be formed using six letters when repetition is not allowed=12
Step-by-step explanation:
dztdxfchvjbkniuklyhj8nuoihyn897uiohy897iuohy87uiohy8nj,bhkbnjomiklj;miojkmojno;ioki987779807u
Answer:
Angle x= 60°
Step-by-step explanation:
For the triangle HIL, you're going to add 30+90=120
Angles in a triangle add up to 180.
So, therefore,
180-120=60 so angle L must equal 60.
HJ is a straight line and angles in a straight line add up to 180.
180-90=90
Angle JIL is equal to 90.
To find y you add 90+45 which equals 135.
Again, angles in a triangle add up to 180.
180-135=45
So,
y = 45
Now we are told that IJK is a right angle and that we are given that IJL is 45. 45 is half of 90 so LJK must be 45.
To find angle JLK we must add angle L and angle y.
60+45=105
Angles in a straight line add up to 180. So,
180-105=75
75 = Angle JLK
75+45=120
Angles in a triangle add up to 180 so,
180-120= 60
Angle x= 60°
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The simplest ratio is 1/3. Equivalent ratios would be 3/9 and 5/15.