ANSWERR ASAP SHOW WORK!!

The width of the blank strip is 30 cm.

Step-by-step explanation:

Let us assume the width of the blank strip  = x

According to the question:

The perimeter of the poster with the blank strip is:

P (1)  = 2(140 + 2x)   + 2 (100 + 2x)

or, P(1) =  8x +  480

Similarly, the perimeter of the printed area is:

P(2) = 2( length + width)

=  2 (140 + 100) = 2 x (240) = 480 cm

or, P(2) = 480 cm

Now,as we know: Perimeter  of poster  =   ( Perimeter of Printer area)

or, P(1) = P(2)

or, 8x  + 480 =

or, 8x  = 720 - 480 =  240

or, x  = 240/8 = 30

or, x  = 30 cm

Hence, the width of the blank strip id 30 cm.