The same number of eggplant seedlings were planted in the two experimental greenhouses, and only fertilizer A was applied to the first greenhouse, but not to the second greenhouse. The first greenhouse produces 1200 kilograms of eggplant and the second greenhouse produces 900kg eggplant. Nothing but water was applied to the two greenhouses
The third greenhouse applied fertilizer B, without fertilizer A, and produced 1000 kilograms of eggplant.
fertilizer A must have led to a higher yield of eggplant in the first greenhouse.