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2015-04-15T22:02:33+05:30

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Basically we need to setup an equation that models the situation and solve it.
Let x=\text{the required number}

Half of x is  \dfrac{x}{2} and one third of  x is  \dfrac{x}{3}.
Add up and set them equal to 15 :
\dfrac{x}{2}+\dfrac{x}{3}=15
write the fractions using a common denominator 6 :
\dfrac{3x}{6}+\dfrac{2x}{6}=15
combine like terms :
\dfrac{5x}{6}=15
multiply each side by \dfrac{6}{5}, the reciprocal of  \dfrac{5}{6} :
\dfrac{6}{5}\left(\dfrac{5x}{6}\right)=\dfrac{6}{5}\left(15\right)
simplify :
x=18

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2015-04-16T01:36:26+05:30

This Is a Certified Answer

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Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
Let the number be  X.
half of the number = X / 2
one third of the number = X / 3

\frac{X}{2}+\frac{X}{3}=15\\\\\frac{3*X+2*X}{6}=15\\\\\frac{5X}{6}=15=3 * 5\\\\X=3*5*\frac{6}{5}=18

so the number is 18.
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verify again:      half of 18 = 9  
               one third of 18  = 6
     add them to get 15.      so it verifies  ok.

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