The surface area of this rectangular prism is 256 square millimeters. What is the value of l? the given numbers are h=4 w=8

To find the value of l, we can use the formula for the surface area of a rectangular prism:

Surface Area = 2lw + 2lh + 2wh

Given that the surface area is 256 square millimeters, we can plug in the given values for h and w:

256 = 2l(8) + 2(4)(8) + 2(4)l

Simplifying this equation, we have:

256 = 16l + 64 + 8l

Combining like terms, we get:

256 = 24l + 64

Subtracting 64 from both sides, we have:

192 = 24l

Dividing both sides by 24, we get:

8 = l

Therefore, the value of l is 8.

4*8*L = 256

L = 256/32 = 8

L = ?

W = 8
h = 4

2W*h + 2L*h = 256 mm^2
2(8*4) + 2(L*4) = 256
64 + 8L = 256
8L = 256-64 = 192
L = 24 mm.

Vol. = L*W*h = 24 * 8 * 4 = 768 mm^3