一个梯形和一个三角形可以拼成一个平行四边形,并且梯形的面积等于三角形面积的3倍,则上下底的关系是?

下底=上底×2
1.1×11×1.1－1.1×1.1－1.1
=1.1×1.1×（11-1）-1.1
=1.1×1.1×10-1.1
=1.1×11-1.1
=1.1×（11-1）
=1.1×10
=11
19.99×36－199.9×1.8＋1999×0.82
=1999×0.36-1999×0.18+1999×0.82
=1999×（0.36-0.18+0.82）
=1999×1
=1999
99999×7＋11111×37
=11111×9×7+11111×37
=11111×63+11111×37
=11111×（63+37）
=11111×100
=1111100
960＋16×0.64＋9.84×64
=960+0.16×64+9.84×64
=960+64×（0.16+9.84）
=960+64×10
=960+640
=1600
11.3×11.87－2.87×11.3＋11.3
=11.3×（11.87-2.87+1）
=11.3×10
=113
﹙12×12×45×10.2﹚÷﹙15×4×0.7×5.1﹚
=（3×4×12×3×15×2×5.1）÷（15×4×0.7×5.1﹚
=（3×12×3×2）÷0.7
=2160/7

19.99*36-199.9*1.8+1999*0.82
=19.99*100*(36/100)-199.9*10*(1.8/10)+1999*0.82
=1999*0.36-1999*0.18+1999*0.82
=1999*(0.36-0.18+0.82)

答案同上

答案同上