Do laws change and even disappear as ethical beliefs change?

Theoretically, yes. If a thing became socially acceptable to the point where say, 75% of the select population was doing something, then the law against said thing would either eventually change or disappear entirely do to the wants of the people. A president has to accommodate its people right? 
Theoretically the answer is yes. 

This is a pretty on point question because all we need to do is replace 's' in the equation with '35'.the calculation will be9.95 + 0.30s = c9.95 + 0.30 (35) = c9.95 + 10.5  = cc = 20.45

Death by starvation.