1/f = 1/d + 1/c, solve for d

Question

1/f = 1/d₁ + 1/d₀, solve for d₁

Answer 1

1/f = 1/d + 1/c

(1/f) -( 1/c) = 1/d

 (1*c)/(f*c)  -   (1*f)/(c*f) = 1/d

  ( c/fc) - ( f / fc) = 1/d

     (c-f) / fc  = 1/d 

        fc/ (c-f) =d     (take reciprocal of each side to get the value of d)

 

So   d= fc/(c-f)