SOLUTION: The average of 5 numbers is 48.The average of the first 3 numbers is 30. The forth number is 20 more then the fifth number. What is the fourth number.

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Question 460393: The average of 5 numbers is 48.The average of the first 3 numbers is 30. The forth number is 20 more then the fifth number. What is the fourth number.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The average of 5 numbers is 48.The average of the first 3 numbers is 30.
The fourth number is 20 more then the fifth number.
What is the fourth number.
:
"The average of 5 numbers is 48"
%28a%2Bb%2Bc%2Bd%2Be%29%2F5 = 48
a + b + c + d + e = 5(48)
a + b + c + d + e = 240
:
"The average of the first 3 numbers is 30."
%28a%2Bb%2Bc%29%2F3 = 30
a + b + c = 90
:
"The fourth number is 20 more then the fifth number."
d = (e+20)
e = (d-20)
:
In the 1st equation replace a+b+c with 90, replace e with (d-20)
90 + d + (d-20) = 240
2d = 240 - 70
2d = 170
d = 170%2F2
d = 85 is the 4th number