In this question, we are presented with a substance X with a solubility of 52.6 g/L, which means that in every 1 liter of volume, we will dissolve 52.6 grams of it at 10°C. Now the question asks about the volume for 43.0 grams at the same temperature:
52.6 grams = 1 Liter
43.0 grams = x Liters
52.6x = 43.0
x = 43.0/52.6
x = 0.817 Liters of volume