Answer:
 -251.9°C
Step-by-step explanation:
Given data: 
Initial volume = 35.0 L 
Initial pressure = 4.62 atm
Initial temperature = -10.0 °C (-10.0 +273 = 263.0 K) 
Final temperature = ?
Final volume = 15.0 L 
Final pressure = 8.71 atm
Solution:
According to general gas equation: 
P₁V₁/T₁ = P₂V₂/T₂ 
Now we will put the values,
 4.62 atm × 35.0 L / 263.0 K = 8.71 atm × 15.0 L /T₂ 
T₂ = 8.71 atm × 15.0 L × 263.0 K / 4.62 atm × 35.0 L 
T₂ = 34360.95 atm.L.K /161.7 atm.L
T₂ = 21.26 K
Kelvin to °C:
 21.26 - 273.15 K = -251.9°C