如图，在四边形ABCD中，AB=30，AD=48，BC=14，且∠ABD+∠BDC=90°，∠ADB+∠DBC=90°．请问：四边形ABCD的面积是多少？
计算：+=﹣= 12×=÷= 0×+9=÷3=×14= 20÷= 1.25××8= 14×÷14×=
+= 6÷=×0.25=÷=×= 9﹣=÷42= 1÷=
口算====÷=×36=÷3= 6÷=
直接写出计算结果．+=×0×27= 6÷=×39= 24÷=×4﹣2= 45÷= 1﹣﹣=+÷+=×÷×=
直接写出得数． 1÷=+=÷=（﹣）×18=÷3=×=﹣=×÷×=
+
=
﹣
= 12×
=
÷
=
+9=
÷3=
×14= 20÷
=
×8= 14×
÷14×
+
= 6÷
=
×0.25=
÷
=
×
= 9﹣
=
÷42= 1÷
=
=
=
=
=
÷
=
×36=
÷3= 6÷
=
+
=
×0×27= 6÷
=
×39= 24÷
=
×4﹣2= 45÷
= 1﹣
﹣
=
+
÷
=
×
÷
×
=
=
+
=
÷
=（
﹣
）×18=
÷3=
×
﹣
=
×
÷
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