First, we should find out what the circumference of one can is and then multiply it by two, because they ask us about two cans.
The formula for calculating the circumference is:
C = 2πr
Good news - we have r! r equals 8.3 cm.
So the circumference of one can, hence length of one piece of paper, equals 2π * 8.3 = 16.6π. Length of two pieces of paper is the result of this multiplication: 2 * 16.6π = 33.2π