Tính nhẩm:
a, 138^2-38^2 b, (10^2+8^2+6^2+4^2+2^2)- (9^2+7^2+5^2+3^2+1^2)
PLZZZ, giúp vs

is there a question?

Step-by-step explanation:

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