How do you solve #0.30(80) + 0.60x = 0.40(80 + x)#?

1 Answer
May 30, 2018

Just a way of thinking: looking for mental shortcuts.

#x=30#

Explanation:

#0.30=3xx1/10#

so #0.3(80)color(white)("dd")=color(white)("dd")3xx80xx1/10color(white)("dd")=color(white)("dd")3xx8color(white)("dd")=color(white)("dd")24#

#0.40(80)color(white)("d")=color(white)("d")4xx80xx1/10color(white)("d")=color(white)("d")4xx8color(white)("d")=color(white)("d")32 #
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Putting it all together we have:

#24+0.6x=32+0.4x#

#0.6x-0.4x=32-24#

#0.2x=6#

#x=(6xx10)/(0.2 xx10)=60/2=30#