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Simplify `(b+10)/(4b-20) - (4b + 20)/(5b-25)`  b+10/4b-20 - 4b+20/5b-25

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rosey-girl | Student, Grade 12 | (Level 1) Valedictorian

Posted November 15, 2012 at 3:01 AM via web

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Simplify `(b+10)/(4b-20) - (4b + 20)/(5b-25)`  

b+10/4b-20 - 4b+20/5b-25

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durbanville | High School Teacher | (Level 1) Educator Emeritus

Posted November 15, 2012 at 4:30 AM (Answer #1)

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= `(b+10)/(4(b- 5)) - (4(b+5))/(5(b-5))`

Lowest common denominator is 20(b-5). Mulitiply each side according to the LCD: 

`therefore = (5(b+10) - 4(4)(b+5))/ (20(b-5))` 

Remove the brackets. Care with the negative (-) sign:

= `(5b + 50 - 16b - 80)/(20(b-5))`

= `(-11b- 30)/(20 (b-5))`

= `(-(11b+30))/(20(b-5))`

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