For these question, it has two separate equations: 2f(a) and f(2a) .
For f(2a) equations its x=2a, so you must substitute 2a into the f(x) equation
For 2f(a), it means the two time of f(a) equation with x=a, so you substitute a inti f(x) equation first, then you multiply it by 2.
This graph shows data up to about 2010. So it couldn't have been drawn before 2010. OF COURSE the data from only 10 years earlier was more reliable than the data that was 120 years old ! It wasn't even measured the same way back then as it is now.
Answer:
the swing on the right is more likely to break
since the vertical component of the tension of the rope has to balance the weight. ie. the resultant tension in the rope is greater
