SOLUTION: the average of 3 numbers is 39. the second is 3 less than twice the first and the third is 6 less than thrice the first. find the 3 numbers.

Question 483543: the average of 3 numbers is 39. the second is 3 less than twice the first and the third is 6 less than thrice the first. find the 3 numbers.
Found 2 solutions by Maths68, MathTherapy:
Answer by Maths68(1474) (Show Source): You can put this solution on YOUR website!
Let first number = x
The second is 3 less than twice the first= 3-2x
The third is 6 less than thrice the first= 6-3x
(first#+second#+third#)/3 = Average
[(6-3x)+(3-2x)+x]/3=39
(6-3x+3-2x+x)/3=39
(9-4x)/3=39 (Multiply by 3 both the sides)
9-4x=117
-4x=117-9
-4x=108
-4x/4=108/4=4x/4 (Divide by 4 both sides)
-x=27
x=-27
the second is 3 less than twice the first= 3-2x = 3-2(-27)=3+54=57
third is 6 less than thrice the first= 6-3x=6-3(-27)=6+81=87
-27,57,87

Answer by MathTherapy(10557) (Show Source): You can put this solution on YOUR website!
the average of 3 numbers is 39. the second is 3 less than twice the first and the third is 6 less than thrice the first. find the 3 numbers.

Let first number be F

We can then say that:

F, or first = F
Second = 2F � 3
Third = 3F - 6

Now, since the average of the numbers is 39, we than have:

6F � 9 = 117 ---- Cross-multiplying
6F = 126

F =

F, or first number =

Then second = 2(21) � 3 = 42 � 3 =
Third = 3(21) � 6 = 63 � 6 =

-----------
Check
-----------
(21 + 39 + 57)/3 = 39
117/3 = 39
39 = 39 (TRUE)
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