The length of a rectangle is 4cm less than twice the width. The perimeter is 58cm. Find the length

Let x be the width so the length will be 2x-4. The perimeter can be found by the equation x+x + (2x-4) + (2x-4) = 58. Notice I repeated the length and the width twice because you know there are two lengths and two widths in a rectangle, so continue solving by combining like terms 6x-8=58 the add 8 to both sides 6x=66 then divide both sides by 6 to obtain x=11, that's the width but they are asking you for the length so we said the length could be found by the equation 2x-4, now plug in the 11, 2 (11) - 4 and solve 22-4 equals 18cm which is the length.