Question 52258
DynoTech Industries = 4 X Ohio plant = 4n
Ohio =  n
If the difference in the ages of the two plants is 9 years, than 
Dynotech - Ohio = 9
.
So,
(4  x Ohio) - (Ohio) = 9
4n - n = 9 [Solve for n]
3n=9
n=3 is the age of the Ohio plant
.
checking:
Dynatech - Ohio = 9
(4)(3)-(3) = 9
12-3=9
9=9 [Checks out]