(2cos 40 - cos 20)/sin 20
$$[2cos^220-2sin^220-cos20]/sin20\\
=[2-2sin^220-2sin^20-cos20]/sin20\\
=[2-4sin^220-cos20]/sin20\\
=2cosec20-4sin20-cot20\\
=\mbox{I am just playing here, Aziz is right, there is not much you can do with this}$$
You can enter it into the web2 calc like this. 
(2*cos(40)-cos(20))/sin(20)
=$${\frac{\left({\mathtt{2}}{\mathtt{\,\times\,}}\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}{\left({\mathtt{40}}^\circ\right)}{\mathtt{\,-\,}}\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}{\left({\mathtt{20}}^\circ\right)}\right)}{\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{sin}}{\left({\mathtt{20}}^\circ\right)}}} = {\mathtt{1.732\: \!050\: \!807\: \!567\: \!060\: \!3}}$$
Okay the answers are different.
Aziz has assumed radians, which is a correct assumption because it you do not specifiy the units then by default it is radians.
I have used degrees because I am used to school students and I assume that is what you actually wanted.
So 2 different interpretations (both reasonable) have produced 2 different answers.