If 1/a + 1/b = 1/c, then c= ?

PLEASE EXPLAIN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

12 POINTS

Respuesta :

[tex] \dfrac{1}{a}+\dfrac{1}{b}=\dfrac{1}{c}|\cdot abc\\
bc+ac=ab\\
c(b+a)=ab\\
c=\dfrac{ab}{a+b}
[/tex]