The passage best supports the statement that a concrete road are reinforced with other material. According to the information given in the passage, steel plays a vital role in keeping the road surface flat.
Steel bars are embedded in concrete so that the stresses cannot crack the slab. Therefore, it indicates that concrete road is reinforced with other material.
If the total amount of swimmers is 40, you can divide it by 8 to get 5 multiples. If three of those 5's belong to the ratio of girls, the equation is 3 x 8. The answer is 24.