A rectengular swimming pool 30m long and 22m wide is made.And a deck of the uniform width is made around the pool,and only 480m^2 deck is made,HOW WIDE SHOULD THE DECK BE?

outside dimensions of deck are L and W

inside dimensions of deck are 30 and 22
so
Area of deck = L W - 660
so
L W - 660 = 480
L W = 1140
if x = deck width
Length L = 30 + 2x
W = 22+2x
so
(22+2x)(30+2x) = 1140
multiply out and solve quadratic