Can someone explain this math problem
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Can someone explain this math problem

[From: ] [author: ] [Date: 12-09-28] [Hit: ]
.2222 + .7 - .5714 = .59/90 = .The answer in the back of your book is incorrect for the problem you posted.......
2/9 + 7/10 + -4/7 = ?
I got 221/630 but the answer in the back of the book shows 59/90... What am I doing wrong?

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Your answer is correct. The lowest common denominator for 9, 10 and 7 is 630. You need to multiply each fraction by a number to raise the denominator to 630:

70*(2/9) + 63*(7/10) - 90*(4/7) = ?

Which gets you:

140/630 + 441/630 - 360/630 = 221/630

Even if you look at it in decimal form:

.2222 + .7 - .5714 = .3508

59/90 = .6556

The answer in the back of your book is incorrect for the problem you posted.

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221/630
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