A tape diagram visualizes the relationship between two quantities in a ratio. A certain number of parts are resembled by what looks like rolls of tape. Each part represents a quantity of the ratio. These parts are divided into equal sections according to the relationship in the ratio. The given tape diagram shows how many erasers there are according to the number of pencils. The same tape diagram can be used for the equivalent ratios. For example, the ratio of $30$ pencils to $10$ erasers can be shown by the tape diagram with a ratio of $3$ to $1.$ In that case, one section of the tape-like parts represents $10$ items.