?- 20%= 530.36

Good attempt anonymous - It was good to see you have a go.  You did make a little mistake though.

To get the value of x

80% x = 530.36

x = 530.36 $$\div$$ 80%

x= 530.36  $$\div$$ 0.80

$${\frac{{\mathtt{530.36}}}{{\mathtt{0.8}}}} = {\mathtt{662.95}}$$

It should not have been 1.2 in the previous answer it should have been 1.25 that is why the answers are different.

x-(20%*x)=530.36

(80%*x)=530.36

We need to get 80%*x back up to 100%*x.

What # can we multiply to 0.80 to get 1

0.80*#=1

0.80*1.2=1

1=1

Now ,back to the problem.

0.80x=530.36

0.80x*1.2=530.36*1.2

x=636.432