Hello! 
We have the following data:  
F (force) =? m (mass) = 40 kg 
a (acceleration) = 0.93 m / s² 
k (spring constant) =? 
x (spring deformation) = 0.82 m 
Let us first find the applied force, through the following formula:


 Now let's find the spring constant, using Hooke's formula
Now let's find the spring constant, using Hooke's formula





Answer: 
We have a spring constant with about 45 N / m