The question provides the concentration of a solution (12% CaCl2) and requests us to calculate how many grams of this solution could be prepared starting from 35g of CaCl2.
Since the concentration of solution is 12%, considering it refers to % in mass, we can write that 12g of CaCl are necessary to prepare 100 g of solution:
12 g of CaCl2 --------------- 100 g of solution
Thus, we can calculate how much solution could be prepared from 35 g of CaCl2:
12 g of CaCl2 --------------- 100 g of solution
35 g of CaCl2 -------------- x
Solving for x, we have that 291.67 g of solution could be prepared from 35g of CaCl2.