20 second problem!!!!!!!!!!

Make $\boxed{ \frac{1}{x} + \frac{1}{y} =a }$ a single fraction

$\frac{y}{xy} + \frac{x}{xy}$

$\frac{y + x}{yx}$ Substitute given values for x + y and xy

$\frac{\frac{3}{4}}{\frac{1}{4}}$

$\frac{ 3 * 4}{1 * 4}$

= $\boxed{3}$

By multiplying (1/xy) and (x+y) i.e. (4)*(3/4), we get the value of a. Hence the correct answer is 3

Divide the given equations to obtain $\dfrac{1}{x} + \dfrac{1}{y} = \dfrac{\frac{3}{4}}{\frac{1}{4}} = \color{#69047E}{\boxed{3}}$ .

a=1/x+1/y=(x+y)/xy=(3/4)/(1/4)=3/4*4/1=3

1/x+1/y= a x+y/xy=a 3/4 / 1/4 =3

(1/x) + (1/y) = (x+y)/xy = (3/4)/(1/4) = 3 = a

divide 1st eqn by 2nd to get a=3