First you add like terms in which this case is -.46x and .16x which equals -.3x then divide 6.6 into -.3 which is -22. x = -22
In order to sole the problem you need to create an equation to model what you are trying to do.
You end up with an equation looking like
25000*0.95^t
25000 is the starting value when t=0
95% is the amount remaining after the 5% decay
0.95 is being raised to the power of t to determine how many times it has decayed
When t=3 the equation should be
25000*0.95^3=21434.375
If it takes an hour to fill 1 tank in 1 hour 1 tank will be full
Add the who numbers: 4 + 2 = 6
You are correct, it's C. 6
4/7 the question is relative