How many fewer grams of #Li_2CO_3#, will dissolve in 225 g of water at 60°C than at 20°C?
Unknown without data....
...you ask us to supply data that you are unwilling to supply yourself. This site provides an idea. A more interesting question is why the solubility of the salt should DECREASE with INCREASING temperature.
That solubility decreases with increasing temperature, points to an entropy effect. The small lithium atom is effectively solvated by several water molecules, and this has a NEGATIVE impact on entropy (i.e. it makes the entropy of the reaction LESS favourable in that in induces solvent order).
The other alkali-metal carbonates have more conventional solubililty profiles, given that as larger cations, they are LESS polarizing and INDUCE less solvent order.