A plastic box has a length 4 cm longer than its width. The area of the rectangular top of the box is 77 square cm. Find the length and width of the box.

the length is 11 cm.

The width is 7 cm.

Step-by-step explanation:

Let L represent the length of the rectangular plastic box.

Let W represent the width of the rectangular plastic box.

The area of the rectangular top of the box is 77 square cm. This means that

LW = 77- - - - - - - ;- - - -1

The plastic box has a length 4 cm longer than its width. This means that

L = W + 4

Substituting L = W + 4 into equation 1, it becomes

(W + 4)W = 77

W² + 4W = 77

W² + 4W - 77 = 0

W² + 11W - 7W - 77 = 0

W(W + 11) - 7(W + 11) = 0

W - 7 = 0 or W + 11 = 0

W = 7 or W = - 11

Since the width cannot be negative, then W = 7cm

L = 77/7 = 11 cm