evaluate this function using f(3/4)
f(x)=x-4/2x-5
f(3/4) = [ x - 4] / [2x - 5] =
[(3/4) - 4] / [ 2(3/4) - 5] =
[3/4 - 16/4] / [ 6/4 - 20/4] =
[-13/4] / [ -14/4] =
(-13/4) * (4 / -14) =
(-13/-14) * (4/4) =
(13/14) * 1 =
13 /14
