Answer:
the measure of the length is 40cm.
Step-by-step explanation:
Formula: P=2L+2W
so 120=2L+2(20)
we want the subject to be L
so 2L=120-40,because 2×20 is 40
and when you sending across the sign will change.
so 2L=80,than we divide both side by 2.
So 80÷2=40,
therefore the answer is 40.
