"9 1/4 ounces of fertilizer, 3/4 ounce of fertilizer for each plant."
Divide the total amt. of fert. by the amt. that goes to each plant:
9 1/4 oz
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(3/4) oz per plant
Convert 9 1/4 to an improper fraction: 9 1/4 = 37/4.
Now divide 37/4 by 3/4, or divide 37 by 3. Result: 12 1/3 plants.
Ms. Marks can fertilize 12 plants and have 1/3 oz of fertilizer left over.