Answer:
8712
Step-by-step explanation:
8,712 square feet
1 Acre = 43,560 Square Feet
then,
Blake has mowed
3
5
of
1
2
an acre
3
5
x
1
2
=
3
10
then,
Blake has already mowed
43,560 x
3
10
= 13,068 square feet
thus,
43,560
2
- 13,068 = 21,780 - 13,068 = 8,712 square feet