4a + 9b = 4c + 9d then a = ?4a − 9b4c − 9db

Here,	4a + 9b	=	4c + 9d
	4a − 9b		4c − 9d

On applying componendoand dividendo , we have

4a + 9b + 4a − 9b

4a + 9b − 4a + 9b

=	4c + 9d + 4c − 9d
	4c + 9d − 4c + 9d

⇒	8a	=	8c	⇒	a	=	c
	18b		18d		b		d