如图，正方形ABCD的边AB、BC分别在三角形BEF的BE、BF边上，顶点D在EF边上，点D把EF分成两段，DE=12米，DF=15米，求两个阴影三角形的面积和．
口算．== 5﹣== 0×1= 1÷===
直接写得数．========
直接写得数+=÷7=×=÷=×8= 9÷= 15×=﹣=÷=×=×=÷=
直接写出得数．+=×=÷6=×8=+= 2﹣= 0+=÷= 1÷=﹣=
直接写得数．+= 1﹣= 1÷=﹣= 9.6÷1.6= 0÷= 51×199≈（+）×12=
=
= 5﹣
=
=
= 1÷
=
=
=
=
=
=
=
=
=
=
=
+
=
÷7=
×
=
÷
=
×8= 9÷
= 15×
=
﹣
=
÷
=
×
=
=
÷
=
+
=
×
=
÷6=
×8=
+
=
= 0+
=
÷
= 1÷
=
﹣
=
+
= 1﹣
= 1÷
=
﹣
=
= 51×199≈（
+
）×12=
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