TRANSPOSITION OF FORMULAE B7

If e =  a(d + f)    make a the subject of the formula.

             (d – f)

Solution

e =  a(d + f)   

         (d – f)

(d – f) x e = a(d + f) x (d – f)   multiply by(d - f) on both sides.

                      (d – f)

(d – f) x e = c(d + m) open the brackets on both sides.

ed – ef = cd + cm

ed – cd = ef + cm  (collect the terms containing d together)

d(e – c) = ef + cm

d(e – c) = ef + cm        Divide by (e - c) on both sides.

  (e – c)    (e – c)

d = ef + cm       

       (e – c)

Hence  d = ef + cm       

                    (e – c)