It tells us the length is 4 meters more than its width, so length = w + 4. We can substitute that equivalent information and the area we were given into the equation:
60 = (w+4) x w
60 = w^2 + 4w
w^2 + 4w - 60 = 0
Then solve using the quadratic formula, which I can't remember...but I'm hoping you can.
