Question

If f(x) is parallel to the line y=3/4x+2/5, which function could be f(x)

Answer 1

A line that is parallel, is one with the same slope. The slope of the line from the equation is y = 3/4x + 2/5, is 3/4. 

Therefore you can put any number instead of 2/5 and the line would be parallel. 
Some examples of f(x) would be:
$f(x) = \frac{3}{4} + 15$
$f(x) = \frac{3}{4} + 253$
$f(x) = \frac{3}{4} - 43$

Hope this helps!