A local park has 70 pigeons that call the park home. Half of the pigeons are black, and 20 percent of the black pigeons are male.  How many more black female pigeons are there than black male pigeons?
Black:70/2=<<70/2=35>>35 pigeons
Black Male: 35(.20)=7 pigeons
35-7=<<35-7=28>>28 female black pigeon
There are 28-7=<<28-7=21>>21 more black female pigeons
#### 21