Answers to practice problems

1) 2x + 10y + 5z = 30 Z

2x = 30

(2/2)x = 30/2

x = 15

10y = 30

(10/10)y = 30/10

y = 3

Y

5z = 30

(5/5)z = 30/5

z = 6

X

Z

2) 5x + 10y + 20z = 40

5x = 40

(5/5)x = 40/5

x = 8

10y = 40

(10/10)y = 40 Y

y = 4

20z = 40

(20/20)z = 40

z = 2

X

3) Volume: 5 x 6 x 4 = 120 cubic units

Surface Area: 5 x 4=20

20 x 2 = 40

6 x 4 = 24

24 x 2

48

5 x 6 = 30

30 x 2 = 60

60 + 48 + 40 = 148

Surface Area= 148 units²

4) Volume : 6 x 12 x 8= 576 cubic units

Surface Area: 8 x 6 = 48

48 x 2 = 96

12 x 6 = 72

72 x 2 = 144

8 x 12 = 96

96 x 2 = 192

96 + 144 + 192 = 432

Surface Area = 432 units²