The quantity of salt in grams needed to complete the experiment is 180 grams.
Ratio expresses the relationship between two or more numbers. It shows the frequency of the number of times that one value is contained within other value(s).
Quantity of salt needed = (grams of baking soda x ratio of salt) / ratio of baking soda
(3 x 420) / 7 = 180 grams
To learn more about ratios, please check: https://brainly.com/question/25927869
