Chapter 4 - Forces and Newton's Laws of Motion - Focus On Concepts - Page 112: 8

(b) $0.8$ is the correct answer.

As the skaters pull the rope, the rope exerts on each skater tension force $T$, which is the only force acting on each of the skater. According to Newton's 2nd Law, $$T=m_{paul}a_{paul}=m_{tom}a_{tom}$$ $$\frac{m_{tom}}{m_{paul}}=\frac{a_{paul}}{a_{tom}}=1.25$$ $$\frac{m_{paul}}{m_{tom}}=\frac{1}{1.25}=0.8$$