Macy’s is having a sale in which all jeans at $30. the sales tax is 8%. if john buys n pairs of jeans during this sale, the total cost of his purchase will be 30n+0.08(30n)

This expression is correct. It shows the price John pays for the jeans on the left side of the + symbol (30n), and the amount of tax he has to pay on the right side of the symbol (0.08(30n)).

Hope this helps!

area of part 1:

a1=base*height/2=(8+2)*(8-2-2-1)/2=10*3/2=15 ft^2

area of part 2:

a2=length*width=(8+2)*1=10 ft2

area of part 3:

a3=length*width=8*2=16 ft2

total shaded area : a1+a2+a3=41 ft2

total area of the reactangle : a=16*8=128 ft2

total area of the nonshaded region : 128-41=87 ft2