Question

On a rainy day, every kid at Margo's school brings a raincoat, an umbrella, or both. 8 percent of the kids bring both. The total number of kids with umbrellas is twice the total number of kids with raincoats. What percent of the kids bring only an umbrella?

Answer 1

1. check the pic at the bottom.

2. Since we are asked for percentage, so a ratio, let  the number of kids with both umbrellas and raincoats be 8. 

Let x be the number of children with raincoats, but not umbrellas
Let y be the number of children with umbrellas but not raincoats.

3. Then, x+y+8=100 (100% is 100, since we assumed 8% to be 8 kids)

 this gives us x+y=92.

4. "The total number of kids with umbrellas is twice the total number of kids with raincoats. " :

                    8+y=2(x+8)
                    8+y=2x+16
                        y-2x=8

5. substitute x=92-y in y-2x=8, we get

y-2(92-y)=8
y-184+2y=8
      3y=192
         y=64
64% ofkids bring only an umbrella.