Question 142478
Okay, let's start with the formula for a perimeter of a triangle, P= a+b+c, eqn1
where a= 1st side, b= 2nd side, & c= 3rd side.
Now the conditions, 
1st cond'n, the length of 2nd side is half that of the 1st side.So "b=(1/2)(a)"----eqn 2
2nd cond'n, the length of the 3rd side is 3 emters less than the 1st side. 
So,  "c= a-3" -- eqn 3
Then, substitute all of these values in eqn 1 we have,
P= a + (1/2)a + a-3
37 = 2a + (1/2)a - 3
37+3= (4a+a)/2
80=5a
16m=a, length of 1st side
For b, as per eqn 2, = (1/2)(16)
b=8m, length of 2nd side
For c, as per eqn 3, = 16-3
c=13m, length of 3rd side
In doubt? Go back eqn 1,
37=16+8+13
37m=37m,  cool!
Thank you,
Jojo