Answer:
For every 2 quarts of water, ¹/₂ cup of vinegar is used.
⇒ To find the amount of vinegar, divide the number of quarts by 4.
⇒ To find the number of quarts, multiply the amount of vinegar by 4.
4 qt water = 4 ÷ 4 = 1 cup vinegar
1¹/₂ cups vinegar = 1¹/₂ x 4 = 6 qt water
8 qt water = 8 ÷ 4 = 2 cup vinegar
Plot the points on the graph (see second attached image).
Draw a line through the points.
Find 3 along the x-axis and trace up to the line. Trace along to the y-axis.
Therefore, Gavin would need to use 12 quarts of water with 3 cups of vinegar.