First we need to find the area of the field
we find the area of the rectangle

now find the area of the half circle, if we join them is a circle

now sum the areas to find the total area of the field

total area is 19417.85 square ft
Now to find the number of 2lb bags
we divide the whole area between the cover of a 2lb bag (500squareft)

we need 38.83 bags of seed to cover the field, as we cannot buy partial bags we must buy 39 bags to cover the field