
Substituting this into the other ODE gives

Since
, it follows that
. The ODE in
has characteristic equation

with roots
, admitting the characteristic solution

From the initial conditions we get



So we have

Take the derivative and multiply it by -1/4 to get the solution for
:

Answer:
divide 64/8 and 27/9 to arrive at 8/3 for 64/27
<span>To find 7% tax on $9.79 multiply by 0.07 getting 0.6853
Then add 9.79 to 0.6853 getting 10.4753 (round to $10.48) </span>
The answer of this is gonna be 7