In math, "of" almost always means "times".
"The property" is 7/8 acre.
So "1/4 of the property" means "1/4 times 7/8 acre".
1/4 x 7/8 = (1 x 7) / (4 x 8)
That's 7/32 .
Mr. Lopez hasn't plowed up anything yet, but his plan is to plow up 7/32 acre for his garden.
