SOLUTION: The sum of three numbers is 55. One number is five more than a second number. It is also twice the third. Find the numbers.

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Question 1061080: The sum of three numbers is 55. One number is five more than a second number. It is also twice the third. Find the numbers.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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The three numbers are a, b, c
write an equation for each statement
Arrange the 2nd and 3rd equations so that b and c are in terms of a

The sum of three numbers is 55.
a + b + c = 55
:
One number is five more than a second number.
a = b + 5
subtract 5 from both sides
b = a - 5
:
It is also twice the third.
a = 2c
divide both sides by 2
c = .5a
:
Substitute for b and c in the first equation
a + (a-5) + .5a = 55
2.5a - 5 = 55
2.5a = 55 + 5
2.5a = 60
a = 60/2.5
a = 24
find b
b = 24 - 5
b = 19
find c
c = .5(24)
c = 12
:
Check in the 1st equation
24 + 19 + 12 = 55