# A question about percentages with one fixed number

I have a rather simple question about percentages that I can't solve for the fourth time. It comes up every few months and I just have to 'guess' the number but there must be a simple formula that I just cant figure out.

Basically it is the following.

y - 40% = 1,80

How do I calculate y?

I know simply adding 40% to 1,80 and then subtracting 40% off the result wont work because the basis for the percentage is different.

What value must I multiply 1,80 by so that when I subtrack 40% of the result I will get back to 1,80?

Thanks

$$y-40\%=1.8 \Leftrightarrow y(1-0.4)=1.8$$
$$0.6\times y=1.8$$
$$y=\frac{1.8}{0.6}=3$$