To prove that lg(4,5-x)=lg4,5-lgx, we need to use the properties of logarithms.

First, let's simplify lg(4,5-x) using the change of base formula for logarithms:

lg(4,5 - x) = lg(5 - x) / lg(4)

Now, let's simplify lg4,5-lgx using the properties of logarithms:

lg(4*5) - lg(x)
= lg(20) - lg(x)
= lg(20/x)

So, lg(4,5-x) = lg(5 - x) / lg(4) = lg(20/x)

Therefore, lg(4,5-x) is not equal to lg4,5-lgx.