2 3/4 acres is the same as 11/4 acres
To find how much of the land is beans, find how much is already taken up, and the rest is beans.
Farmland-Corn-Potatoes-Wheat=Beans
1-(1/4)-(1/12)-(5/8)=1/24
Corn: (1/4)x(11/4)=11/16 acres
Potatoes: (1/12)x(11/4)=11/48 acres
Wheat: (5/8)x(11/4)=55/32 acres or 1 23/32 acres
Beans: (1/24)x(11/4)=11/96 acres