8x-2y+5z=-5
5x+2y-3z=7

1 Add

2

y

2y to both sides.

8

x

+

5

z

=

−

5

+

2

y

8x+5z=−5+2y

2 Regroup terms.

8

x

+

5

z

=

2

y

−

5

8x+5z=2y−5

3 Subtract

5

z

5z from both sides.

8

x

=

2

y

−

5

−

5

z

8x=2y−5−5z

4 Divide both sides by

8

8.

x

=

2

y

−

5

−

5

z

8

1 Subtract

2

y

2y from both sides.

5

x

−

3

z

=

7

−

2

y

5x−3z=7−2y

2 Add

3

z

3z to both sides.

5

x

=

7

−

2

y

+

3

z

5x=7−2y+3z

3 Divide both sides by

5

5.

x

=

7

−

2

y

+

3

z

5

x=

5

7−2y+3z

​

I hope this help you

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