Plz answer !

julia did an experiment to study the
solubility of two substances. she poured 100ml of water at 20°c into each of two beakers labeled a and b. she put 50g of substance a in the beaker labeled a and 50g of substance b in the beaker labeled b. the solution in both beakers was stirred for 1 minute. the amount of substance left undissolved in the beakers was weighed. the experiment was repeated for different temperatures of water and the observations were recorded as shown.

mass of undissolved substance at different temperatures (grams)

substance

20°c 40°c 60°c 80°c

a | 40 37 34 30

b | 15 14 13 12