Which expression is equivalent to 3x+4y\frac{3}{x} + \frac{4}{y}x3+y4?
7xy\frac{7}{xy}xy7
3y+4xxy\frac{3y+4x}{xy}xy3y+4x
3x+4yxy\frac{3x+4y}{xy}xy3x+4y
12xy\frac{12}{xy}xy12