Remark
Let's establish some ground rules here. Confine yourself to 20oC
She puts in 50 grams of substance and 40 won't ionize or act like sugar (which is referred to as a colloidal suspension. microscopic sugar molecules don't dissolve: they just sort of float around. Just hope that Julie didn't use sugar in her experiment.
Solubility means mixes with (usually) water. Substance A is acting as though it is insoluble or very nearly so.
Now temperature increases the solubility of both substances. So here are your 3 rules.
Answer, Part B
1. Solubility means ability to mix or ionize, usually with water.
2. The more soluble substances have a SMALLER residue. So B is the more soluble substance.
3. The higher the temperature, the more soluble the substance. That's because the residue is going down or getting smaller when the temperature is raised.