Because 3 is less than or equal to 4, you would round down, it would be 33. I am talking about the three(s) after the decimal.
P = 2l + 2w
P = 2(x + 3) + 2(7)
P = 2(x) + 2(3) + 14
P = 2x + 6 + 14
P = 2x + 20
A = lw
A= 7(x + 3)
A = 7(x) + 7(3)
A = 7x + 21
3x is the cost for x notebooks
24*3 is the cost of 24 notebooks
that is 24*3=72