To solve means we need an equation, and only an expression has been given. Therefore, I assume that the space in the expression should be equals: -(.5x-3)/4=x/5. Multiplying through by 20: -5(0.5x-3)=4x; -2.5x+15=4x; 6.5x=15; x=15/6.5=30/13=2.31 approx.
Another interpretation is: evaluate the expression -(.5x-3)/4 for (x=5): -(2.5-3)/4=-(-0.5)/4=0.5/4=1/8 or 0.125.