SOLUTION: Four numbers have a sum of 9900. The second exceeds the first by one-seventh of the first. The third exceeds the sum of the first two by 300. The fourth exceeds the sum of the f

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Question 332138: Four numbers have a sum of 9900. The second exceeds the
first by one-seventh of the first. The third exceeds the sum
of the first two by 300. The fourth exceeds the sum of the
first three by 300. Find the four numbers.

Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!

Four numbers have a sum of 9900. The second exceeds the
first by one-seventh of the first. The third exceeds the sum
of the first two by 300. The fourth exceeds the sum of the
first three by 300. Find the four numbers.

Let a,b,c, and d respectively represent the first four numbers.

>>...Four numbers have a sum of 9900...<<

That tells us that

 a + b + c + d = 9900

>>...The second exceeds the first by one-seventh of the first...<<

That tells us that

b = a + 1%2F7a

>>...The third exceeds the sum of the first two by 300...<<

That tells us that

c = (a + b) + 300

>>...The fourth exceeds the sum of the first three by 300...<<

That tells us that

d = (a + b + c) + 300

So we have the system:



Simplify by removing parentheses and
multiplying the second one through by 7
to clear of fractions.



Simplify by combining terms in the 2nd one:



Simplify by rearranging terms:



Add the 1st and 4th equations term by term:

system%28%0D%0Aa+%2B+b+%2B+c+%2B+d+=+9900%2C%0D%0A-a+-+b+-+c+%2B+d=300%29

2d=10200

d=5100

So substitute that in the first three equations: 



system%28%0D%0Aa+%2B+b+%2B+c+=+4800%2C%0D%0A-8a+%2B+7b+=+0%2C%0D%0A-a-b+%2Bc+=+300%29
 
Add the 1st and 3rd equation:

system%28%0D%0Aa+%2B+b+%2B+c+=+4800%2C%0D%0A-a-b+%2Bc+=+300%29

2c=5100
c=2550

Substitute that in the first two
equations:

system%28%0D%0Aa+%2B+b+%2B+c+=+4800%2C%0D%0A-8a+%2B+7b+=+0%29

system%28%0D%0Aa+%2B+b+%2B+2550+=+4800%2C%0D%0A-8a+%2B+7b+=+0%29

Rearrange:

system%28%0D%0Aa+%2B+b+=+2250%2C%0D%0A-8a+%2B+7b+=+0%29

To eliminate the a's multiply the first equation by 8

system%28%0D%0A8a+%2B+8b+=+18000%2C%0D%0A-8a+%2B+7b+=+0%29

Add term by term:

15b=18000
b=1200

a = 1050, b = 1200, c = 2550, d = 5100 

Edwin