The question is incomplete, here is the complete question:
A chemistry student needs 75 g of thiophene foran experiment. He has available 0.50 kg of a 29.3% w/w solution of thiophene in carbon tetrachloride.
Calculate the mass of solution the student should use. If there's not enough solution, press the "No solution" button.
<u>Answer:</u> The mass of solution the student should use is 255.97 grams
<u>Explanation:</u>
We are given:
Mass of thiophene needed = 75 gram
29.3 % w/w thiophene solution
This means that 29.3 grams of thiophene is present in 100 grams of solution
Applying unitary method:
If 29.3 grams of thiophene is present in 100 grams of solution
So, 75 grams of thiophene will be present in = 
Given amount of solution = 0.50 kg = 500 grams (Conversion factor: 1 kg = 1000 g)
Hence, the mass of solution the student should use is 255.97 grams