In a 70-30 mix of isopropyl alcohol and water, which is the solvent? Or are they both solvents?

GENERALLY, we call the one there in the larger about the solvent and the other one the solute.

Water

In a 70-30 mix of isopropyl alcohol and water, the solvent is water. Generally, the substance present in larger quantity is considered the solvent, while the substance in smaller quantity is referred to as the solute. In this case, water is present in a higher proportion (70%), making it the solvent, while isopropyl alcohol is present in a lesser proportion (30%), making it the solute.