Omgerd! i need some !

the length of the top of a rectangular-shaped deck is 6 meters longer than its width. if the area of the top of the deck is 72 square meters, what is its length in meters?

Area is LxW
here, W+6 = L
so substitute this relation into the area formula to get
(W+6)W = 72
W² + 6W = 72
W² + 6W - 72 = 0
this is a quadratic equation.  you can factor or use quadratic formula to get 
W= 6 or -12
-12 doesn't make sense for width so choose W=6.  Since length is 6 meters longer than width the length is
L = 6+6= 12.
check by seeing 6*12 = 72