I already answered it on one of your posts with the same question, but here I'll tell you again :)
Okay so first set up the equation(s) for this situation. In this case, you need two equations: B=3/4A (In which B= Benjamin and A=Ann) S=2B (In which S= Siti and B= Benjamin) Now first solve for the first equation where you can plug in A for 35kg: B=3/A B=3/4*35 B=26.25 Now you can use that value and use it for the second equation. Plug in B with 26.25: S=2B S=2*26.25 S=52.5 So Siti has a mass of 52.5 kg
