Question 1095475
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Your equation is 


{{{(1/2)*x*(x+20)}}} = 750,


where x is the unknown wide.


=====>  x*(x+20) = 750*2 = 1500.


Solve it by any method you know.


I solve it mentally:  x = 30 ft.


<U>Answer</U>.  The width = 30 ft.  The height is 50 ft.
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