According to this question, a sulfur-containing compound is said to contain 15 percent by mass of sulfur. This means that 15% of the total mass of the compound is the mass of sulfur in the compound.
The question further states that there is a total of 200g of the compound containing sulfur, this means that the mass of sulfur can be calculated this:
Mass of sulfur = 15% of 200g
15/100 × 200g
15 × 2
30g
Hence, there are 30g of sulfur in 200g of the sulfur containing compound.
Photosynthesis converts carbon dioxide and water into oxygen and glucose. Cellular respiration converts oxygen and glucose into water and carbon dioxide.