3/2y-3/2y+4

Question

=
rational expression reduce to lcd

Answer 1

The way you typed it ....
3/2y-3/2y+4
= 4

If you meant ....
3/(2y-3) - 3/(2y+4) then
= (3(2y+4) - 3(2y-3))/((2y-3)(2y+4))
= (6y+12-6y+9)/((2y-3)(2y+4))
= 21/((2y-3)(2y+4))

Answer 2

3/(2y) - 3/(2y+4)
= [3(2y+4) -3(2y]/[(2y)(2y+4)]
= [6y +12 -6y]/[(2y)(2y+4)]
= 12/[(2y)(2y+4)]

Answer 3

I interpreted your problem differently from Reiny due to the ambiguous lack of parentheses.