I'm horrible at explaining, but basically the y-axis is increasing by 3's so it's not negative, and to find the y-axis, we simply put a 0 ontop of the 1 in the x-axis, and across that we get -2 because the y-axis is increasing by 3's.
So sorry for my messy explanation, but I hope it helps :)
$38*75% (the amount of the original price you pay) is $<span>28.50 $</span>28.50*1.06 (the cost of the book (100%) and the cost of the tax on top (6%)) is $<span>30.21 The customer pays a total of $</span><span>30.21 for the book</span>
