See picture for solution to your problem.
I believe the right equation for determining the area of a trapezoid is as below,
A = h(a + b)/2
To determine the expression for b which is the length of one of its bases, we multiply the equation by 2.
2A = h(a + b)
Then, divide both sides of the equation by h,
2A/h = a + b
Then, subtract a from both sides of the equation,
2A/h - a = b
Lastly, interchange the sides of the equation to reveal the answer.
<em> </em>
<em> b = 2A/h - a </em>
<h2>Given :</h2>
<h2>Solution : </h2>

Through the statement above we have,
_____________________________

The answer is the first one
Answer:
let x be the total amount of gallons he bought
$16.80÷$1.40 = x
16.80÷1.40=12
x=12
Step-by-step explanation: