standard_description: Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
problem_activity: Task
The lot that Dana is buying for her new one story house is 35 yards by 50 yards. Dana’s house plans show that her house will cover 1,600 square feet of land. What percent of Dana’s lot will not be covered by the house? Explain your reasoning.


aligns: no