Adozen of books are rs 680 at a profit of rs 140. what is the cost of one book?

= Rs 68.3

Step-by-step explanation:

The cost of one dozen = 680 + 140 = 820

To find the cost of one, divide 820 by 12.  (Dozen = 12)

820/12 = Rs 68.3

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