Math hep: turning a ratio into a percentage?

i got this question wrong on my test and i wanted to know how to do it

the question:

I lay down tiles in the garden to make a pond, the ratio of grey to black tiles is 3:1

what percentage of the design is black

Math hep: turning a ratio into a percentage?
3+1= 4

1/4=25/100

25 percent are black
Reply:There are 3 grey tiles for 1 black tile, so for 4 tiles (you have to take the sum), there is 1 black tile, so we have

1 black tile on 4 this is 1/4 = 0,25 or 100x(1/4)=25 percent !
Reply:If there are 3 gray tiles for every black tile, there is 1 black tile for every 4 tiles total. Therefore, 1/4=.25, or 25%.

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