The formula of an area of a trapezoid:
a,b - a baseh - a height
We have:
substitute
The equation looks like this:
26=x*3.5+8.50
where x is the number of pen you bought.
We solve it like this:
first, we subtract 8.50 from both sides:
17.50 =3.5*x
now we divide both sides by 3.5:
5=x
so you purchased 5 pens.
Yup it's correct :) good job!
Answer:
The answer to the question provided is