8x2 to the second power plus 8.
<span>The best answer is C.add 2 to both sides of the equation.
</span>5=x-2
5+2=x-2+2
7=x-0
x=7
Capacity of the tank = 45 gallon
At the beginning of Oct., amount of oil in the tank = 45*0.8 = 36 gallons
At the end of Oct., amount of oil in the tank = 45*1/3 = 15 gallons
So, amount of oil used during Oct = (36-15) = 21 gallons