A stick is twice as long as a piece of string. If you have 10 strings and 10 sticks laid out in a line, the line measures 90 inches. How long is the stick?

The stick is 6 inches. if the stick is 6 and the string is 3 then the stick is double the string. if you multiply them both by ten because there is 10 each, you get 60 and 30. if you add them together you get 90 inches so the stick is 6 in. :))