Try using the formula Pi (r) squared (1.5cm)
To find the number of notebooks Steve bought you will subtract the amount he paid for his backpack from the total amount, and then you will divide the remaining amount by $3.98 to find the number of notebooks.
($43.78 - $27.86)/$3.98
$15.92/$3.98
4
Steve bought 4 notebooks.
5 is your answer 4 divided by 20 is 5
76/9 = 8.444444444444 > 8.0 or 8.45