Exercice

: (a-3 b)/(5 b) = (c-3 d)/(5 c) true OR false?

IT'S FALSE!!!!.

If  a/b  =  c/d

then subtract 3 from both sides:

--->     a/b - 3  =  c/d - 3

which becomes:  a/b - 3b/b  =  c/d - 3d/d

--->     (a - 3b)/b  =  (c - 3d)/d

Multiply both sides by  1/5:

--->     (a - 3b)/(5b)  =  (c - 3d)/(5d)

Did you mistype the problem?

If a/b=c/d then prove that

(a-3b)/(5.b) = (c-3*d)/(5c)

A very simple proof:let a=1, b=2, c=3, d=6 so that we have 1/2=3/6.Now substitute as follows: (1 - 3*2)/(5*2)=(3- 3*6)/(5*3)

We have(-5)/10=-15/15

Therfore -1/5 =-1 !!!!!!!!!!!!!!!!!!!!!!!! Where did get this gem from?

(a-3b)/(5.b) = (c-3*d)/(5c)

SORRY!! I meant: -1/2=-1 instead of -1/5=-1