You had $20 to spend on seven avocados. After buying them you had $6. How much did each avocado cost?

They each cost 2 dollars

$20 - $6 = $14 so she spent $14 on avocados. if she bought 7 of them, each avocado would equal the same amount so 14 ÷ 7 = 2 so she spent $2 on each avocado.