Question 26215
Ok first I will assume that when you said side A is tice side B, you meant twice, OK?.  You need to know several things to find this answer.  First, of course, you need the formula for the perimeter  which is side +side +side.  You have 3 sides.  We will call them side A B and C.  You know they equal 98 meters.  now, to find the sides.  First look at the question.  The only variable you would have that does not have a number involved is your B side.  So we will set up our equation as if we are solving for B, ok.  this is what you know from the equation
B=B
A= 2B  (side A is twice side B)
C=2B-2  (side C is 2 meters shorter than side A, which is 2B)

To get perimeter you add these three together and set them equal to 98

2B + B + 2B - 2 = 98    (do you see how I set A + B + C = 98)
5B-2=98  (combine like terms)
5B=100    (solve using algebra)
B=20    (side B = 20 meters)
A= 2*20=40 (side A= 40 meters)
C= 2*20-2=38 (side C = 38 meters)

check by adding A + B + C = 98
20+40+38=98

I hope this helps, if you need further assistance, please let me know.
A.