Answer:

Let's assume that the phone is a rectangle with length 14 cm and width w cm.

The perimeter of a rectangle is given by the formula P = 2(l + w), where P is the perimeter, l is the length, and w is the width.

Substituting the given values, we get:

42 = 2(14 + w)

Simplifying this equation, we get:

21 = 14 + w

Subtracting 14 from both sides, we get:

w = 7

Therefore, the width of the phone is 7 cm.