as you can see, there is a pattern in the numbers. first, you add the term with 3, then subtract the following with 2. therefore, when we get to the sixth term 9, we will subtract 2 from it, thus getting 7. then, we add 7 and 3, to get the next term, which is 10, and so on and so forth.
$45-$3 you would do this to take out the processing fee. $42/ $6 this is because each shirt cost $6 the equation would be (45-3) / 6= 7] your answer would be 7 shirts
is already in simplest form.