[填空题]
A farmer is going to fence twox :abuppt0 n5hu,1/2bag5m stpl,b4 6p 1 w ael;yxjmob9n*d7 equal adjacent parcels of land. These parcels share one side (which also requires fencing) as shown in the following diagram. The farmer has only 80 7;*1nmpxe6j4,bw bd l l9apyometres of fence.
1.Write down the equation for the total length of the fence, 80m, in terms of x and y. ax+by=c a = b = c =
2.Write down the total area of both parcels of land in terms of x.
3.Find the maximum area, in $m^2$, of one parcel of land. ≈