You can actually draw infinite number of quadrilaterals with the given dimensions but do not worry each one is going to have the same area.
Try constructing it in the easiest way possible. Here's one, first construct AB & AD perpendicular to each other (this is right-angled triangle at A with BD=30).
Now, you have BC=40, CD=50 & diagonal BD=30 (observe ∆BCD is right-angled at angle DBC).
Two right triangles BAD & DBC, their corresponding areas are ½(18)(24) and ½(30)(40).
Area of quadrilateral is (216)+(600) = 816.