How do you solve #4/(b-3.9)=2/(b+1)#?

1 Answer
Alan P.
Jul 29, 2017

#color(green)(b=-5.9)#

Explanation:

Given
#color(white)("xxx")4/(b-3.9)=2/(b+1)#

If we multiply both sides by #(b-3.9)(b+1)#
(sometimes called "cross-multiplying")
we get
#color(white)("xxx")4(b+1)=2(b-3.9)#

Expanding
#color(white)("xxx")4b+4=2b-7.8#

Simplifying
#color(white)("xxx")2b=-11.8#

#color(white)("xxx")b=-5.9#

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