Answer with Step-by-step explanation:
Let a mass weighing 16 pounds stretches a spring
feet.
Mass=
Mass=

Mass,m=
Slug
By hook's law




A damping force is numerically equal to 1/2 the instantaneous velocity

Equation of motion :

Using this equation



Auxillary equation





Complementary function

To find the particular solution using undetermined coefficient method



This solution satisfied the equation therefore, substitute the values in the differential equation


Comparing on both sides


Adding both equation then, we get


Substitute the value of B in any equation



Particular solution, 
Now, the general solution

From initial condition
x(0)=2 ft
x'(0)=0
Substitute the values t=0 and x(0)=2




Substitute x'(0)=0




Substitute the values then we get

That is 62x9 which is 9x2=18 and 9x60=540 so you then add 540+18=558 chairs
Answer:
Using PEMDAS, you should get the answer of 5.