SOLUTION: one number is 2/5 of another . the sum of their two numbers is 21.find the two numbers. rational expressions

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Question 681861: one number is 2/5 of another . the sum of their two numbers is 21.find the two numbers.
rational expressions
Answer by ReadingBoosters(3246) About Me  (Show Source):
You can put this solution on YOUR website!
x is one number
y is another number
...
x+=+%282%2F5%29y
x+y = 21 : rearrange as x = 21-y
...
21 - y = (2/5)y
...
Multiply the entire equation by 5
5%2821%29+-+5y+=+5%282%2F5%29y
105 - 5y = 2y
...
Isolate the y variable
105 = 2y + 5y
105 = 7y
...
Divide both sides by 7
highlight_green%28y+=+15%29
x = 21-15 = highlight_green%28x=6%29
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