you had $26 in your pocket. you purchased x pens at $3.50 each. you now have $8.50 in your pocket write and solve an equation to find the number of pens purchased.

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.