Question 658697
If we call the width w, then the length is w+3. We know that the perimeter is the sum of all 4 sides, that is two widths and two heights. That give the following equation:

2w+2(w+3)=30

Then solve for w. Remember, what you do to one side, you must do to the other so it continues to have equal sides of the equation.

2w+2w+6=30
4w+6=30
4w+6-6=30-6
4w+0=24
4w=24
1/4*4w=24*1/4
1*w=6
w=6

If the width=6 meters, the length must be w+3 or 9 meters. Check to see if the perimeter is 30 meters.