How Many Feet Is Three Tenth Of A Mile F?

I'm not sure what your final "F" means; however :
One mile = 5280 feet
3/10 of one mile = 528 x 3 =    1584 ft

1 mile = 5280 ft.  Multiply that by .3

5,280 feet divided by 3 will provide the number of feet in 1/3 rd of a mile.