so, she bought 15 gallons of gas last week
Explanation
Step 1
Let
36 gallons this week
x= number of gallons of gas Shane bought las week
this amount is 6 gallons more than twice the amount of gas he bought last week , then
[tex]36=2x+6[/tex]Step 2
solve for x
[tex]\begin{gathered} 36=2x+6 \\ \text{subtract 6 in both sides} \\ 36-6=2x+6-6 \\ 30=2x \\ \text{divide each side by 2} \\ \frac{30}{2}=\frac{2x}{2} \\ x=15 \end{gathered}[/tex]so, she bought 15 gallons of gas last week
