Question 565488
The volume of the box can be calculated by length times width times height, or {{{volume = length*width*height}}}.
height = 8 inches
width = x
length = x + 3 inches (three inches more than the width)
volume = 144 {{{in^2}}}
Simply plug these into your formula for volume:
{{{volume = length*width*height}}}
{{{144 = (x + 3)(x)(8)}}} <==YOUR FORMULA
Multiply 8 and x: {{{144 = (x + 3)(8x)}}}
Multiply x + 3 and 8x: {{{144 = 8x^2 + 24x}}}
Subtract 144 from both sides of the equation: {{{0 = 8x^2 + 24x - 144}}}
Divide everything by 8: {{{0 = x^2 + 3x - 18}}}
Factor: 0 = (x - 3)(x + 6)
Put each part equal to 0 and solve for x:
x - 3 = 0 and x + 6 = 0
x = 3 or -6
Since a measurement cannot be negative, the width must be 3 INCHES.
Hope I helped! =)