11、Grandpa Li used a batch of fertilizers to fertilize the wheat fields he contracted. If he applies 6 kilograms per mu, then he would be short of 300 kilograms of fertilizers; if he applies 5 kilograms per mu, then he would have 200 kilograms of fertilizers left. Therefore, Grandpa Li contracted $\qquad$ mu of wheat fields, and this batch of fertilizers has $\qquad$ kilograms.
11, 500; 2700
Solution: Let the wheat field be $\mathrm{x}$ acres. If 6 kilograms are applied per acre, then 300 kilograms of fertilizer are lacking, which means the existing fertilizer is $6 x-300$ (kilograms); if 5 kilograms are applied per acre, then 200 kilograms of fertilizer are left over, which means the existing fertilizer should be $5 x+200$ (kilograms). Since the amount of existing fertilizer is a constant, we have $6 x-300=5 x+200$, solving for $x=500$ (acres).

The amount of existing fertilizer is $5 \times 500+200=2700$ (kilograms).