Surface are of a rectangular prism = 2(l x w + l x h + w x h) = 2(10 x 3 + 10x + 3x) = 2(30 + 13x) = 60 + 26x
Volume of a rectangular prism = l x w x h = 10 * 3 * x = 30x
Since surface area = volume
60 + 26x = 30x
4x = 60
x = 15 in
1) 12 * 9 = 108 cm² - part 1
2) 12 - 3 - 3 = 6 cm
3) 6 * 4 = 24 cm² - part 2
4) 108 + 24 =
132 cm ² - the area.