To find the equation that represents the relationship shown in the graph, we follow the formula for direct proportionality:
\[ \text{Cost} = k \times \text{Weight} \]
Where \( k \) is the constant of proportionality. From the information given, we see that the line passes through the point (2, 10), which means when the weight is 2 ounces, the cost is 10 dollars.
Now we can use this point to find \( k \):
\[ 10 = k \times 2 \]
To solve for \( k \), divide both sides by 2:
\[ k = \frac{10}{2} = 5 \]
Now we can complete the equation with the found constant of proportionality:
\[ \text{Cost} = 5 \times \text{Weight} \]
Thus, the completed equation is:
Cost = 5 × Weight