Math question, maybe I'm just dumb?

The paint company wants to know how much water they must add to their current 10 gal jugs that are already mixed at a 9 gal paint : 1 gal water ratio..

Let x = the total number of gallons after adding the additional water

There are currently 9 gal of water in a 90% (paint:water) mixture; we need to determine how many gal total will result in an 80% (paint:water) mixture

So 9 gal is 80% of what volume

9 = 0.8x

x = 9/(0.8) = 11.25

So if we already have 10 gal, then we need to add 1.25 gal more of water to each 10 gal jug

9 gal paint / 11.25 gal total = 0.8 or 80%

they have ten gallon of a mixture of paint and water.

the mix is 10% water

so there is 1 gallon of water and 9 gallons of paint, at the start

Now they want to thin the paint to a 80/20 mix of paint to water.

How much water total do they need in the final mixture?

9/80 = x / 20

180/ 80 = x

2.25 gallon = x --> This is the TOTAL amount of water needed.

the mix already has 1 gallon of water in it

1.25 gal of water needs to be added

Yeah, you're just dumb.