如果平行四边形的底不变,高扩大3倍,那么平行四边形的面积 .
÷25= :8=27÷ =3.
0.75=12÷ = :12== %= 折.
0.75=12÷ =9: = %
0.7=7÷ = :30== %
3÷5= = :15== %