Respuesta :
(a+c)/(b+d) = (a-c) / (b-d)
cross multiply
ab -ad +bc -cd = ab +ad -bc -cd
cancelling ab and -cd, on both sides of eqn
combining like terms
-2ad = -2bc
dividing both sides by (-2)
ad =bc
dividing both sides by (bd)
a/b = c/d,,,,,,,,,as required
cross multiply
ab -ad +bc -cd = ab +ad -bc -cd
cancelling ab and -cd, on both sides of eqn
combining like terms
-2ad = -2bc
dividing both sides by (-2)
ad =bc
dividing both sides by (bd)
a/b = c/d,,,,,,,,,as required